Preparation for including docs in round-trip with OSS
diff --git a/googlemock/docs/cook_book.md b/googlemock/docs/cook_book.md
index d040209..285e770 100644
--- a/googlemock/docs/cook_book.md
+++ b/googlemock/docs/cook_book.md
@@ -1,28 +1,63 @@
-## Google Mock Cookbook
+## Googletest Mocking (gMock) Cookbook
<!-- GOOGLETEST_CM0011 DO NOT DELETE -->
-You can find recipes for using Google Mock here. If you haven't yet,
-please read the [ForDummies](for_dummies.md) document first to make sure you understand
-the basics.
+You can find recipes for using gMock here. If you haven't yet, please read
+[this](for_dummies.md) first to make sure you understand the basics.
-**Note:** Google Mock lives in the `testing` name space. For
-readability, it is recommended to write `using ::testing::Foo;` once in
-your file before using the name `Foo` defined by Google Mock. We omit
-such `using` statements in this page for brevity, but you should do it
-in your own code.
+**Note:** gMock lives in the `testing` name space. For readability, it is
+recommended to write `using ::testing::Foo;` once in your file before using the
+name `Foo` defined by gMock. We omit such `using` statements in this section for
+brevity, but you should do it in your own code.
-# Creating Mock Classes #
+### Creating Mock Classes
-## Mocking Private or Protected Methods ##
+#### Dealing with unprotected commas
-You must always put a mock method definition (`MOCK_METHOD*`) in a
-`public:` section of the mock class, regardless of the method being
-mocked being `public`, `protected`, or `private` in the base class.
-This allows `ON_CALL` and `EXPECT_CALL` to reference the mock function
-from outside of the mock class. (Yes, C++ allows a subclass to specify
-a different access level than the base class on a virtual function.)
-Example:
+Unprotected commas, i.e. commas which are not surrounded by parentheses, prevent
+`MOCK_METHOD` from parsing its arguments correctly:
+
+```cpp
+class MockFoo {
+ public:
+ MOCK_METHOD(std::pair<bool, int>, GetPair, ()); // Won't compile!
+ MOCK_METHOD(bool, CheckMap, (std::map<int, double>, bool)); // Won't compile!
+};
+```
+
+Solution 1 - wrap with parentheses:
+
+```cpp
+class MockFoo {
+ public:
+ MOCK_METHOD((std::pair<bool, int>), GetPair, ());
+ MOCK_METHOD(bool, CheckMap, ((std::map<int, double>), bool));
+};
+```
+
+Note that wrapping a return or argument type with parentheses is, in general,
+invalid C++. `MOCK_METHOD` removes the parentheses.
+
+Solution 2 - define an alias:
+
+```cpp
+class MockFoo {
+ public:
+ using BoolAndInt = std::pair<bool, int>;
+ MOCK_METHOD(BoolAndInt, GetPair, ());
+ using MapIntDouble = std::map<int, double>;
+ MOCK_METHOD(bool, CheckMap, (MapIntDouble, bool));
+};
+```
+
+#### Mocking Private or Protected Methods
+
+You must always put a mock method definition (`MOCK_METHOD`) in a `public:`
+section of the mock class, regardless of the method being mocked being `public`,
+`protected`, or `private` in the base class. This allows `ON_CALL` and
+`EXPECT_CALL` to reference the mock function from outside of the mock class.
+(Yes, C++ allows a subclass to change the access level of a virtual function in
+the base class.) Example:
```cpp
class Foo {
@@ -40,16 +75,16 @@
class MockFoo : public Foo {
public:
...
- MOCK_METHOD1(Transform, bool(Gadget* g));
+ MOCK_METHOD(bool, Transform, (Gadget* g), (override));
// The following must be in the public section, even though the
// methods are protected or private in the base class.
- MOCK_METHOD0(Resume, void());
- MOCK_METHOD0(GetTimeOut, int());
+ MOCK_METHOD(void, Resume, (), (override));
+ MOCK_METHOD(int, GetTimeOut, (), (override));
};
```
-## Mocking Overloaded Methods ##
+#### Mocking Overloaded Methods
You can mock overloaded functions as usual. No special attention is required:
@@ -71,31 +106,31 @@
class MockFoo : public Foo {
...
- MOCK_METHOD1(Add, int(Element x));
- MOCK_METHOD2(Add, int(int times, Element x));
+ MOCK_METHOD(int, Add, (Element x), (override));
+ MOCK_METHOD(int, Add, (int times, Element x), (override));
- MOCK_METHOD0(GetBar, Bar&());
- MOCK_CONST_METHOD0(GetBar, const Bar&());
+ MOCK_METHOD(Bar&, GetBar, (), (override));
+ MOCK_METHOD(const Bar&, GetBar, (), (const, override));
};
```
-**Note:** if you don't mock all versions of the overloaded method, the
-compiler will give you a warning about some methods in the base class
-being hidden. To fix that, use `using` to bring them in scope:
+**Note:** if you don't mock all versions of the overloaded method, the compiler
+will give you a warning about some methods in the base class being hidden. To
+fix that, use `using` to bring them in scope:
```cpp
class MockFoo : public Foo {
...
using Foo::Add;
- MOCK_METHOD1(Add, int(Element x));
+ MOCK_METHOD(int, Add, (Element x), (override));
// We don't want to mock int Add(int times, Element x);
...
};
```
-## Mocking Class Templates ##
+#### Mocking Class Templates
-To mock a class template, append `_T` to the `MOCK_*` macros:
+You can mock class templates just like any class.
```cpp
template <typename Elem>
@@ -111,20 +146,20 @@
template <typename Elem>
class MockStack : public StackInterface<Elem> {
...
- MOCK_CONST_METHOD0_T(GetSize, int());
- MOCK_METHOD1_T(Push, void(const Elem& x));
+ MOCK_METHOD(int, GetSize, (), (override));
+ MOCK_METHOD(void, Push, (const Elem& x), (override));
};
```
-## Mocking Nonvirtual Methods ##
+#### Mocking Non-virtual Methods {#MockingNonVirtualMethods}
-Google Mock can mock non-virtual functions to be used in what we call _hi-perf
-dependency injection_.
+gMock can mock non-virtual functions to be used in Hi-perf dependency
+injection.<!-- GOOGLETEST_CM0016 DO NOT DELETE -->.
-In this case, instead of sharing a common base class with the real
-class, your mock class will be _unrelated_ to the real class, but
-contain methods with the same signatures. The syntax for mocking
-non-virtual methods is the _same_ as mocking virtual methods:
+In this case, instead of sharing a common base class with the real class, your
+mock class will be *unrelated* to the real class, but contain methods with the
+same signatures. The syntax for mocking non-virtual methods is the *same* as
+mocking virtual methods (just don't add `override`):
```cpp
// A simple packet stream class. None of its members is virtual.
@@ -140,27 +175,25 @@
// GetPacket() and NumberOfPackets().
class MockPacketStream {
public:
- MOCK_CONST_METHOD1(GetPacket, const Packet*(size_t packet_number));
- MOCK_CONST_METHOD0(NumberOfPackets, size_t());
+ MOCK_METHOD(const Packet*, GetPacket, (size_t packet_number), (const));
+ MOCK_METHOD(size_t, NumberOfPackets, (), (const));
...
};
```
-Note that the mock class doesn't define `AppendPacket()`, unlike the
-real class. That's fine as long as the test doesn't need to call it.
+Note that the mock class doesn't define `AppendPacket()`, unlike the real class.
+That's fine as long as the test doesn't need to call it.
-Next, you need a way to say that you want to use
-`ConcretePacketStream` in production code and to use `MockPacketStream`
-in tests. Since the functions are not virtual and the two classes are
-unrelated, you must specify your choice at _compile time_ (as opposed
-to run time).
+Next, you need a way to say that you want to use `ConcretePacketStream` in
+production code, and use `MockPacketStream` in tests. Since the functions are
+not virtual and the two classes are unrelated, you must specify your choice at
+*compile time* (as opposed to run time).
-One way to do it is to templatize your code that needs to use a packet
-stream. More specifically, you will give your code a template type
-argument for the type of the packet stream. In production, you will
-instantiate your template with `ConcretePacketStream` as the type
-argument. In tests, you will instantiate the same template with
-`MockPacketStream`. For example, you may write:
+One way to do it is to templatize your code that needs to use a packet stream.
+More specifically, you will give your code a template type argument for the type
+of the packet stream. In production, you will instantiate your template with
+`ConcretePacketStream` as the type argument. In tests, you will instantiate the
+same template with `MockPacketStream`. For example, you may write:
```cpp
template <class PacketStream>
@@ -175,8 +208,8 @@
Then you can use `CreateConnection<ConcretePacketStream>()` and
`PacketReader<ConcretePacketStream>` in production code, and use
-`CreateConnection<MockPacketStream>()` and
-`PacketReader<MockPacketStream>` in tests.
+`CreateConnection<MockPacketStream>()` and `PacketReader<MockPacketStream>` in
+tests.
```cpp
MockPacketStream mock_stream;
@@ -186,15 +219,14 @@
... exercise reader ...
```
-## Mocking Free Functions ##
+#### Mocking Free Functions
-It's possible to use Google Mock to mock a free function (i.e. a
-C-style function or a static method). You just need to rewrite your
-code to use an interface (abstract class).
+It's possible to use gMock to mock a free function (i.e. a C-style function or a
+static method). You just need to rewrite your code to use an interface (abstract
+class).
-Instead of calling a free function (say, `OpenFile`) directly,
-introduce an interface for it and have a concrete subclass that calls
-the free function:
+Instead of calling a free function (say, `OpenFile`) directly, introduce an
+interface for it and have a concrete subclass that calls the free function:
```cpp
class FileInterface {
@@ -207,34 +239,91 @@
public:
...
virtual bool Open(const char* path, const char* mode) {
- return OpenFile(path, mode);
+ return OpenFile(path, mode);
}
};
```
-Your code should talk to `FileInterface` to open a file. Now it's
-easy to mock out the function.
+Your code should talk to `FileInterface` to open a file. Now it's easy to mock
+out the function.
-This may seem much hassle, but in practice you often have multiple
-related functions that you can put in the same interface, so the
-per-function syntactic overhead will be much lower.
+This may seem like a lot of hassle, but in practice you often have multiple
+related functions that you can put in the same interface, so the per-function
+syntactic overhead will be much lower.
-If you are concerned about the performance overhead incurred by
-virtual functions, and profiling confirms your concern, you can
-combine this with the recipe for [mocking non-virtual methods](#mocking-nonvirtual-methods).
+If you are concerned about the performance overhead incurred by virtual
+functions, and profiling confirms your concern, you can combine this with the
+recipe for [mocking non-virtual methods](#MockingNonVirtualMethods).
-## The Nice, the Strict, and the Naggy ##
+#### Old-Style `MOCK_METHODn` Macros
-If a mock method has no `EXPECT_CALL` spec but is called, Google Mock
-will print a warning about the "uninteresting call". The rationale is:
+Before the generic `MOCK_METHOD` macro was introduced, mocks where created using
+a family of macros collectively called `MOCK_METHODn`. These macros are still
+supported, though migration to the new `MOCK_METHOD` is recommended.
- * New methods may be added to an interface after a test is written. We shouldn't fail a test just because a method it doesn't know about is called.
- * However, this may also mean there's a bug in the test, so Google Mock shouldn't be silent either. (Note that the user should [*not* add an `EXPECT_CALL()`](https://github.com/google/googletest/blob/master/googlemock/docs/CookBook.md#knowing-when-to-expect) to suppress the warning, even if they think the call is harmless).
+The macros in the `MOCK_METHODn` family differ from `MOCK_METHOD`:
-However, sometimes you may want to suppress all "uninteresting call"
-warnings, while sometimes you may want the opposite, i.e. to treat all
-of them as errors. Google Mock lets you make the decision on a
-per-mock-object basis.
+* The general structure is `MOCK_METHODn(MethodName, ReturnType(Args))`,
+ instead of `MOCK_METHOD(ReturnType, MethodName, (Args))`.
+* The number `n` must equal the number of arguments.
+* When mocking a const method, one must use `MOCK_CONST_METHODn`.
+* When mocking a class template, the macro name must be suffixed with `_T`.
+* In order to specify the call type, the macro name must be suffixed with
+ `_WITH_CALLTYPE`, and the call type is the first macro argument.
+
+Old macros and their new equivalents:
+
+<a name="table99"></a>
+<table border="1" cellspacing="0" cellpadding="1">
+<tr> <th colspan=2> Simple </th></tr>
+<tr> <td> Old </td> <td> `MOCK_METHOD1(Foo, bool(int))` </td> </tr>
+<tr> <td> New </td> <td> `MOCK_METHOD(bool, Foo, (int))` </td> </tr>
+
+<tr> <th colspan=2> Const Method </th></tr> <tr> <td> Old </td> <td>
+`MOCK_CONST_METHOD1(Foo, bool(int))` </td> </tr> <tr> <td> New </td> <td>
+`MOCK_METHOD(bool, Foo, (int), (const))` </td> </tr>
+
+<tr> <th colspan=2> Method in a Class Template </th></tr> <tr> <td> Old </td>
+<td> `MOCK_METHOD1_T(Foo, bool(int))` </td> </tr> <tr> <td> New </td> <td>
+`MOCK_METHOD(bool, Foo, (int))` </td> </tr>
+
+<tr> <th colspan=2> Const Method in a Class Template </th></tr> <tr> <td> Old
+</td> <td> `MOCK_CONST_METHOD1_T(Foo, bool(int))` </td> </tr> <tr> <td> New
+</td> <td> `MOCK_METHOD(bool, Foo, (int), (const))` </td> </tr>
+
+<tr> <th colspan=2> Method with Call Type </th></tr> <tr> <td> Old </td> <td>
+`MOCK_METHOD1_WITH_CALLTYPE(STDMETHODCALLTYPE, Foo, bool(int))` </td> </tr> <tr>
+<td> New </td> <td> `MOCK_METHOD(bool, Foo, (int),
+(Calltype(STDMETHODCALLTYPE)))` </td> </tr>
+
+<tr> <th colspan=2> Const Method with Call Type </th></tr> <tr> <td> Old</td>
+<td> `MOCK_CONST_METHOD1_WITH_CALLTYPE(STDMETHODCALLTYPE, Foo, bool(int))` </td>
+</tr> <tr> <td> New </td> <td> `MOCK_METHOD(bool, Foo, (int), (const,
+Calltype(STDMETHODCALLTYPE)))` </td> </tr>
+
+<tr> <th colspan=2> Method with Call Type in a Class Template </th></tr> <tr>
+<td> Old </td> <td> `MOCK_METHOD1_T_WITH_CALLTYPE(STDMETHODCALLTYPE, Foo,
+bool(int))` </td> </tr> <tr> <td> New </td> <td> `MOCK_METHOD(bool, Foo, (int),
+(Calltype(STDMETHODCALLTYPE)))` </td> </tr>
+
+<tr> <th colspan=2> Const Method with Call Type in a Class Template </th></tr>
+<tr> <td> Old </td> <td> `MOCK_CONST_METHOD1_T_WITH_CALLTYPE(STDMETHODCALLTYPE,
+Foo, bool(int))` </td> </tr> <tr> <td> New </td> <td> `MOCK_METHOD(bool, Foo,
+(int), (const, Calltype(STDMETHODCALLTYPE)))` </td> </tr>
+
+</table>
+
+#### The Nice, the Strict, and the Naggy {#NiceStrictNaggy}
+
+If a mock method has no `EXPECT_CALL` spec but is called, we say that it's an
+"uninteresting call", and the default action (which can be specified using
+`ON_CALL()`) of the method will be taken. Currently, an uninteresting call will
+also by default cause gMock to print a warning. (In the future, we might remove
+this warning by default.)
+
+However, sometimes you may want to ignore these uninteresting calls, and
+sometimes you may want to treat them as errors. gMock lets you make the decision
+on a per-mock-object basis.
Suppose your test uses a mock class `MockFoo`:
@@ -246,10 +335,9 @@
}
```
-If a method of `mock_foo` other than `DoThis()` is called, it will be
-reported by Google Mock as a warning. However, if you rewrite your
-test to use `NiceMock<MockFoo>` instead, the warning will be gone,
-resulting in a cleaner test output:
+If a method of `mock_foo` other than `DoThis()` is called, you will get a
+warning. However, if you rewrite your test to use `NiceMock<MockFoo>` instead,
+you can suppress the warning:
```cpp
using ::testing::NiceMock;
@@ -261,8 +349,8 @@
}
```
-`NiceMock<MockFoo>` is a subclass of `MockFoo`, so it can be used
-wherever `MockFoo` is accepted.
+`NiceMock<MockFoo>` is a subclass of `MockFoo`, so it can be used wherever
+`MockFoo` is accepted.
It also works if `MockFoo`'s constructor takes some arguments, as
`NiceMock<MockFoo>` "inherits" `MockFoo`'s constructors:
@@ -277,8 +365,8 @@
}
```
-The usage of `StrictMock` is similar, except that it makes all
-uninteresting calls failures:
+The usage of `StrictMock` is similar, except that it makes all uninteresting
+calls failures:
```cpp
using ::testing::StrictMock;
@@ -293,19 +381,49 @@
}
```
-There are some caveats though (I don't like them just as much as the
-next guy, but sadly they are side effects of C++'s limitations):
+NOTE: `NiceMock` and `StrictMock` only affects *uninteresting* calls (calls of
+*methods* with no expectations); they do not affect *unexpected* calls (calls of
+methods with expectations, but they don't match). See
+[Understanding Uninteresting vs Unexpected Calls](#uninteresting-vs-unexpected).
- 1. `NiceMock<MockFoo>` and `StrictMock<MockFoo>` only work for mock methods defined using the `MOCK_METHOD*` family of macros **directly** in the `MockFoo` class. If a mock method is defined in a **base class** of `MockFoo`, the "nice" or "strict" modifier may not affect it, depending on the compiler. In particular, nesting `NiceMock` and `StrictMock` (e.g. `NiceMock<StrictMock<MockFoo> >`) is **not** supported.
- 1. The constructors of the base mock (`MockFoo`) cannot have arguments passed by non-const reference, which happens to be banned by the [Google C++ style guide](https://google.github.io/styleguide/cppguide.html).
- 1. During the constructor or destructor of `MockFoo`, the mock object is _not_ nice or strict. This may cause surprises if the constructor or destructor calls a mock method on `this` object. (This behavior, however, is consistent with C++'s general rule: if a constructor or destructor calls a virtual method of `this` object, that method is treated as non-virtual. In other words, to the base class's constructor or destructor, `this` object behaves like an instance of the base class, not the derived class. This rule is required for safety. Otherwise a base constructor may use members of a derived class before they are initialized, or a base destructor may use members of a derived class after they have been destroyed.)
+There are some caveats though (I dislike them just as much as the next guy, but
+sadly they are side effects of C++'s limitations):
-Finally, you should be **very cautious** about when to use naggy or strict mocks, as they tend to make tests more brittle and harder to maintain. When you refactor your code without changing its externally visible behavior, ideally you should't need to update any tests. If your code interacts with a naggy mock, however, you may start to get spammed with warnings as the result of your change. Worse, if your code interacts with a strict mock, your tests may start to fail and you'll be forced to fix them. Our general recommendation is to use nice mocks (not yet the default) most of the time, use naggy mocks (the current default) when developing or debugging tests, and use strict mocks only as the last resort.
+1. `NiceMock<MockFoo>` and `StrictMock<MockFoo>` only work for mock methods
+ defined using the `MOCK_METHOD` macro **directly** in the `MockFoo` class.
+ If a mock method is defined in a **base class** of `MockFoo`, the "nice" or
+ "strict" modifier may not affect it, depending on the compiler. In
+ particular, nesting `NiceMock` and `StrictMock` (e.g.
+ `NiceMock<StrictMock<MockFoo> >`) is **not** supported.
+2. `NiceMock<MockFoo>` and `StrictMock<MockFoo>` may not work correctly if the
+ destructor of `MockFoo` is not virtual. We would like to fix this, but it
+ requires cleaning up existing tests. http://b/28934720 tracks the issue.
+3. During the constructor or destructor of `MockFoo`, the mock object is *not*
+ nice or strict. This may cause surprises if the constructor or destructor
+ calls a mock method on `this` object. (This behavior, however, is consistent
+ with C++'s general rule: if a constructor or destructor calls a virtual
+ method of `this` object, that method is treated as non-virtual. In other
+ words, to the base class's constructor or destructor, `this` object behaves
+ like an instance of the base class, not the derived class. This rule is
+ required for safety. Otherwise a base constructor may use members of a
+ derived class before they are initialized, or a base destructor may use
+ members of a derived class after they have been destroyed.)
-## Simplifying the Interface without Breaking Existing Code ##
+Finally, you should be **very cautious** about when to use naggy or strict
+mocks, as they tend to make tests more brittle and harder to maintain. When you
+refactor your code without changing its externally visible behavior, ideally you
+shouldn't need to update any tests. If your code interacts with a naggy mock,
+however, you may start to get spammed with warnings as the result of your
+change. Worse, if your code interacts with a strict mock, your tests may start
+to fail and you'll be forced to fix them. Our general recommendation is to use
+nice mocks (not yet the default) most of the time, use naggy mocks (the current
+default) when developing or debugging tests, and use strict mocks only as the
+last resort.
-Sometimes a method has a long list of arguments that is mostly
-uninteresting. For example,
+#### Simplifying the Interface without Breaking Existing Code {#SimplerInterfaces}
+
+Sometimes a method has a long list of arguments that is mostly uninteresting.
+For example:
```cpp
class LogSink {
@@ -318,13 +436,12 @@
};
```
-This method's argument list is lengthy and hard to work with (let's
-say that the `message` argument is not even 0-terminated). If we mock
-it as is, using the mock will be awkward. If, however, we try to
-simplify this interface, we'll need to fix all clients depending on
-it, which is often infeasible.
+This method's argument list is lengthy and hard to work with (the `message`
+argument is not even 0-terminated). If we mock it as is, using the mock will be
+awkward. If, however, we try to simplify this interface, we'll need to fix all
+clients depending on it, which is often infeasible.
-The trick is to re-dispatch the method in the mock class:
+The trick is to redispatch the method in the mock class:
```cpp
class ScopedMockLog : public LogSink {
@@ -343,67 +460,104 @@
// void Log(LogSeverity severity,
// const string& file_path,
// const string& message);
- MOCK_METHOD3(Log, void(LogSeverity severity, const string& file_path,
- const string& message));
+ MOCK_METHOD(void, Log,
+ (LogSeverity severity, const string& file_path,
+ const string& message));
};
```
-By defining a new mock method with a trimmed argument list, we make
-the mock class much more user-friendly.
+By defining a new mock method with a trimmed argument list, we make the mock
+class more user-friendly. <!-- GOOGLETEST_CM0017 DO NOT DELETE -->
-## Alternative to Mocking Concrete Classes ##
+This technique may also be applied to make overloaded methods more amenable to
+mocking. For example, when overloads have been used to implement default
+arguments:
-Often you may find yourself using classes that don't implement
-interfaces. In order to test your code that uses such a class (let's
-call it `Concrete`), you may be tempted to make the methods of
-`Concrete` virtual and then mock it.
+```cpp
+class MockTurtleFactory : public TurtleFactory {
+ public:
+ Turtle* MakeTurtle(int length, int weight) override { ... }
+ Turtle* MakeTurtle(int length, int weight, int speed) override { ... }
+
+ // the above methods delegate to this one:
+ MOCK_METHOD(Turtle*, DoMakeTurtle, ());
+};
+```
+
+This allows tests that don't care which overload was invoked to avoid specifying
+argument matchers:
+
+```cpp
+ON_CALL(factory, DoMakeTurtle)
+ .WillByDefault(MakeMockTurtle());
+```
+
+#### Alternative to Mocking Concrete Classes
+
+Often you may find yourself using classes that don't implement interfaces. In
+order to test your code that uses such a class (let's call it `Concrete`), you
+may be tempted to make the methods of `Concrete` virtual and then mock it.
Try not to do that.
-Making a non-virtual function virtual is a big decision. It creates an
-extension point where subclasses can tweak your class' behavior. This
-weakens your control on the class because now it's harder to maintain
-the class' invariants. You should make a function virtual only when
-there is a valid reason for a subclass to override it.
+Making a non-virtual function virtual is a big decision. It creates an extension
+point where subclasses can tweak your class' behavior. This weakens your control
+on the class because now it's harder to maintain the class invariants. You
+should make a function virtual only when there is a valid reason for a subclass
+to override it.
-Mocking concrete classes directly is problematic as it creates a tight
-coupling between the class and the tests - any small change in the
-class may invalidate your tests and make test maintenance a pain.
+Mocking concrete classes directly is problematic as it creates a tight coupling
+between the class and the tests - any small change in the class may invalidate
+your tests and make test maintenance a pain.
-To avoid such problems, many programmers have been practicing "coding
-to interfaces": instead of talking to the `Concrete` class, your code
-would define an interface and talk to it. Then you implement that
-interface as an adaptor on top of `Concrete`. In tests, you can easily
-mock that interface to observe how your code is doing.
+To avoid such problems, many programmers have been practicing "coding to
+interfaces": instead of talking to the `Concrete` class, your code would define
+an interface and talk to it. Then you implement that interface as an adaptor on
+top of `Concrete`. In tests, you can easily mock that interface to observe how
+your code is doing.
This technique incurs some overhead:
- * You pay the cost of virtual function calls (usually not a problem).
- * There is more abstraction for the programmers to learn.
+* You pay the cost of virtual function calls (usually not a problem).
+* There is more abstraction for the programmers to learn.
However, it can also bring significant benefits in addition to better
testability:
- * `Concrete`'s API may not fit your problem domain very well, as you may not be the only client it tries to serve. By designing your own interface, you have a chance to tailor it to your need - you may add higher-level functionalities, rename stuff, etc instead of just trimming the class. This allows you to write your code (user of the interface) in a more natural way, which means it will be more readable, more maintainable, and you'll be more productive.
- * If `Concrete`'s implementation ever has to change, you don't have to rewrite everywhere it is used. Instead, you can absorb the change in your implementation of the interface, and your other code and tests will be insulated from this change.
+* `Concrete`'s API may not fit your problem domain very well, as you may not
+ be the only client it tries to serve. By designing your own interface, you
+ have a chance to tailor it to your need - you may add higher-level
+ functionalities, rename stuff, etc instead of just trimming the class. This
+ allows you to write your code (user of the interface) in a more natural way,
+ which means it will be more readable, more maintainable, and you'll be more
+ productive.
+* If `Concrete`'s implementation ever has to change, you don't have to rewrite
+ everywhere it is used. Instead, you can absorb the change in your
+ implementation of the interface, and your other code and tests will be
+ insulated from this change.
-Some people worry that if everyone is practicing this technique, they
-will end up writing lots of redundant code. This concern is totally
-understandable. However, there are two reasons why it may not be the
-case:
+Some people worry that if everyone is practicing this technique, they will end
+up writing lots of redundant code. This concern is totally understandable.
+However, there are two reasons why it may not be the case:
- * Different projects may need to use `Concrete` in different ways, so the best interfaces for them will be different. Therefore, each of them will have its own domain-specific interface on top of `Concrete`, and they will not be the same code.
- * If enough projects want to use the same interface, they can always share it, just like they have been sharing `Concrete`. You can check in the interface and the adaptor somewhere near `Concrete` (perhaps in a `contrib` sub-directory) and let many projects use it.
+* Different projects may need to use `Concrete` in different ways, so the best
+ interfaces for them will be different. Therefore, each of them will have its
+ own domain-specific interface on top of `Concrete`, and they will not be the
+ same code.
+* If enough projects want to use the same interface, they can always share it,
+ just like they have been sharing `Concrete`. You can check in the interface
+ and the adaptor somewhere near `Concrete` (perhaps in a `contrib`
+ sub-directory) and let many projects use it.
-You need to weigh the pros and cons carefully for your particular
-problem, but I'd like to assure you that the Java community has been
-practicing this for a long time and it's a proven effective technique
-applicable in a wide variety of situations. :-)
+You need to weigh the pros and cons carefully for your particular problem, but
+I'd like to assure you that the Java community has been practicing this for a
+long time and it's a proven effective technique applicable in a wide variety of
+situations. :-)
-## Delegating Calls to a Fake ##
+#### Delegating Calls to a Fake {#DelegatingToFake}
-Some times you have a non-trivial fake implementation of an
-interface. For example:
+Some times you have a non-trivial fake implementation of an interface. For
+example:
```cpp
class Foo {
@@ -415,59 +569,58 @@
class FakeFoo : public Foo {
public:
- virtual char DoThis(int n) {
+ char DoThis(int n) override {
return (n > 0) ? '+' :
- (n < 0) ? '-' : '0';
+ (n < 0) ? '-' : '0';
}
- virtual void DoThat(const char* s, int* p) {
+ void DoThat(const char* s, int* p) override {
*p = strlen(s);
}
};
```
-Now you want to mock this interface such that you can set expectations
-on it. However, you also want to use `FakeFoo` for the default
-behavior, as duplicating it in the mock object is, well, a lot of
-work.
+Now you want to mock this interface such that you can set expectations on it.
+However, you also want to use `FakeFoo` for the default behavior, as duplicating
+it in the mock object is, well, a lot of work.
-When you define the mock class using Google Mock, you can have it
-delegate its default action to a fake class you already have, using
-this pattern:
+When you define the mock class using gMock, you can have it delegate its default
+action to a fake class you already have, using this pattern:
```cpp
-using ::testing::_;
-using ::testing::Invoke;
-
class MockFoo : public Foo {
public:
- // Normal mock method definitions using Google Mock.
- MOCK_METHOD1(DoThis, char(int n));
- MOCK_METHOD2(DoThat, void(const char* s, int* p));
+ // Normal mock method definitions using gMock.
+ MOCK_METHOD(char, DoThis, (int n), (override));
+ MOCK_METHOD(void, DoThat, (const char* s, int* p), (override));
// Delegates the default actions of the methods to a FakeFoo object.
// This must be called *before* the custom ON_CALL() statements.
void DelegateToFake() {
- ON_CALL(*this, DoThis(_))
- .WillByDefault(Invoke(&fake_, &FakeFoo::DoThis));
- ON_CALL(*this, DoThat(_, _))
- .WillByDefault(Invoke(&fake_, &FakeFoo::DoThat));
+ ON_CALL(*this, DoThis).WillByDefault([this](int n) {
+ return fake_.DoThis(n);
+ });
+ ON_CALL(*this, DoThat).WillByDefault([this](const char* s, int* p) {
+ fake_.DoThat(s, p);
+ });
}
+
private:
FakeFoo fake_; // Keeps an instance of the fake in the mock.
};
```
-With that, you can use `MockFoo` in your tests as usual. Just remember
-that if you don't explicitly set an action in an `ON_CALL()` or
-`EXPECT_CALL()`, the fake will be called upon to do it:
+With that, you can use `MockFoo` in your tests as usual. Just remember that if
+you don't explicitly set an action in an `ON_CALL()` or `EXPECT_CALL()`, the
+fake will be called upon to do it.:
```cpp
using ::testing::_;
TEST(AbcTest, Xyz) {
MockFoo foo;
- foo.DelegateToFake(); // Enables the fake for delegation.
+
+ foo.DelegateToFake(); // Enables the fake for delegation.
// Put your ON_CALL(foo, ...)s here, if any.
@@ -477,71 +630,87 @@
int n = 0;
EXPECT_EQ('+', foo.DoThis(5)); // FakeFoo::DoThis() is invoked.
- foo.DoThat("Hi", &n); // FakeFoo::DoThat() is invoked.
+ foo.DoThat("Hi", &n); // FakeFoo::DoThat() is invoked.
EXPECT_EQ(2, n);
}
```
**Some tips:**
- * If you want, you can still override the default action by providing your own `ON_CALL()` or using `.WillOnce()` / `.WillRepeatedly()` in `EXPECT_CALL()`.
- * In `DelegateToFake()`, you only need to delegate the methods whose fake implementation you intend to use.
- * The general technique discussed here works for overloaded methods, but you'll need to tell the compiler which version you mean. To disambiguate a mock function (the one you specify inside the parentheses of `ON_CALL()`), see the "Selecting Between Overloaded Functions" section on this page; to disambiguate a fake function (the one you place inside `Invoke()`), use a `static_cast` to specify the function's type. For instance, if class `Foo` has methods `char DoThis(int n)` and `bool DoThis(double x) const`, and you want to invoke the latter, you need to write `Invoke(&fake_, static_cast<bool (FakeFoo::*)(double) const>(&FakeFoo::DoThis))` instead of `Invoke(&fake_, &FakeFoo::DoThis)` (The strange-looking thing inside the angled brackets of `static_cast` is the type of a function pointer to the second `DoThis()` method.).
- * Having to mix a mock and a fake is often a sign of something gone wrong. Perhaps you haven't got used to the interaction-based way of testing yet. Or perhaps your interface is taking on too many roles and should be split up. Therefore, **don't abuse this**. We would only recommend to do it as an intermediate step when you are refactoring your code.
+* If you want, you can still override the default action by providing your own
+ `ON_CALL()` or using `.WillOnce()` / `.WillRepeatedly()` in `EXPECT_CALL()`.
+* In `DelegateToFake()`, you only need to delegate the methods whose fake
+ implementation you intend to use.
-Regarding the tip on mixing a mock and a fake, here's an example on
-why it may be a bad sign: Suppose you have a class `System` for
-low-level system operations. In particular, it does file and I/O
-operations. And suppose you want to test how your code uses `System`
-to do I/O, and you just want the file operations to work normally. If
-you mock out the entire `System` class, you'll have to provide a fake
-implementation for the file operation part, which suggests that
-`System` is taking on too many roles.
+* The general technique discussed here works for overloaded methods, but
+ you'll need to tell the compiler which version you mean. To disambiguate a
+ mock function (the one you specify inside the parentheses of `ON_CALL()`),
+ use [this technique](#SelectOverload); to disambiguate a fake function (the
+ one you place inside `Invoke()`), use a `static_cast` to specify the
+ function's type. For instance, if class `Foo` has methods `char DoThis(int
+ n)` and `bool DoThis(double x) const`, and you want to invoke the latter,
+ you need to write `Invoke(&fake_, static_cast<bool (FakeFoo::*)(double)
+ const>(&FakeFoo::DoThis))` instead of `Invoke(&fake_, &FakeFoo::DoThis)`
+ (The strange-looking thing inside the angled brackets of `static_cast` is
+ the type of a function pointer to the second `DoThis()` method.).
-Instead, you can define a `FileOps` interface and an `IOOps` interface
-and split `System`'s functionalities into the two. Then you can mock
-`IOOps` without mocking `FileOps`.
+* Having to mix a mock and a fake is often a sign of something gone wrong.
+ Perhaps you haven't got used to the interaction-based way of testing yet. Or
+ perhaps your interface is taking on too many roles and should be split up.
+ Therefore, **don't abuse this**. We would only recommend to do it as an
+ intermediate step when you are refactoring your code.
-## Delegating Calls to a Real Object ##
+Regarding the tip on mixing a mock and a fake, here's an example on why it may
+be a bad sign: Suppose you have a class `System` for low-level system
+operations. In particular, it does file and I/O operations. And suppose you want
+to test how your code uses `System` to do I/O, and you just want the file
+operations to work normally. If you mock out the entire `System` class, you'll
+have to provide a fake implementation for the file operation part, which
+suggests that `System` is taking on too many roles.
-When using testing doubles (mocks, fakes, stubs, and etc), sometimes
-their behaviors will differ from those of the real objects. This
-difference could be either intentional (as in simulating an error such
-that you can test the error handling code) or unintentional. If your
-mocks have different behaviors than the real objects by mistake, you
-could end up with code that passes the tests but fails in production.
+Instead, you can define a `FileOps` interface and an `IOOps` interface and split
+`System`'s functionalities into the two. Then you can mock `IOOps` without
+mocking `FileOps`.
-You can use the _delegating-to-real_ technique to ensure that your
-mock has the same behavior as the real object while retaining the
-ability to validate calls. This technique is very similar to the
-delegating-to-fake technique, the difference being that we use a real
-object instead of a fake. Here's an example:
+#### Delegating Calls to a Real Object
+
+When using testing doubles (mocks, fakes, stubs, and etc), sometimes their
+behaviors will differ from those of the real objects. This difference could be
+either intentional (as in simulating an error such that you can test the error
+handling code) or unintentional. If your mocks have different behaviors than the
+real objects by mistake, you could end up with code that passes the tests but
+fails in production.
+
+You can use the *delegating-to-real* technique to ensure that your mock has the
+same behavior as the real object while retaining the ability to validate calls.
+This technique is very similar to the [delegating-to-fake](#DelegatingToFake)
+technique, the difference being that we use a real object instead of a fake.
+Here's an example:
```cpp
-using ::testing::_;
using ::testing::AtLeast;
-using ::testing::Invoke;
class MockFoo : public Foo {
public:
MockFoo() {
// By default, all calls are delegated to the real object.
- ON_CALL(*this, DoThis())
- .WillByDefault(Invoke(&real_, &Foo::DoThis));
- ON_CALL(*this, DoThat(_))
- .WillByDefault(Invoke(&real_, &Foo::DoThat));
+ ON_CALL(*this, DoThis).WillByDefault([this](int n) {
+ return real_.DoThis(n);
+ });
+ ON_CALL(*this, DoThat).WillByDefault([this](const char* s, int* p) {
+ real_.DoThat(s, p);
+ });
...
}
- MOCK_METHOD0(DoThis, ...);
- MOCK_METHOD1(DoThat, ...);
+ MOCK_METHOD(char, DoThis, ...);
+ MOCK_METHOD(void, DoThat, ...);
...
private:
Foo real_;
};
+
...
-
MockFoo mock;
-
EXPECT_CALL(mock, DoThis())
.Times(3);
EXPECT_CALL(mock, DoThat("Hi"))
@@ -549,17 +718,16 @@
... use mock in test ...
```
-With this, Google Mock will verify that your code made the right calls
-(with the right arguments, in the right order, called the right number
-of times, etc), and a real object will answer the calls (so the
-behavior will be the same as in production). This gives you the best
-of both worlds.
+With this, gMock will verify that your code made the right calls (with the right
+arguments, in the right order, called the right number of times, etc), and a
+real object will answer the calls (so the behavior will be the same as in
+production). This gives you the best of both worlds.
-## Delegating Calls to a Parent Class ##
+#### Delegating Calls to a Parent Class
-Ideally, you should code to interfaces, whose methods are all pure
-virtual. In reality, sometimes you do need to mock a virtual method
-that is not pure (i.e, it already has an implementation). For example:
+Ideally, you should code to interfaces, whose methods are all pure virtual. In
+reality, sometimes you do need to mock a virtual method that is not pure (i.e,
+it already has an implementation). For example:
```cpp
class Foo {
@@ -573,28 +741,28 @@
class MockFoo : public Foo {
public:
// Mocking a pure method.
- MOCK_METHOD1(Pure, void(int n));
+ MOCK_METHOD(void, Pure, (int n), (override));
// Mocking a concrete method. Foo::Concrete() is shadowed.
- MOCK_METHOD1(Concrete, int(const char* str));
+ MOCK_METHOD(int, Concrete, (const char* str), (override));
};
```
Sometimes you may want to call `Foo::Concrete()` instead of
-`MockFoo::Concrete()`. Perhaps you want to do it as part of a stub
-action, or perhaps your test doesn't need to mock `Concrete()` at all
-(but it would be oh-so painful to have to define a new mock class
-whenever you don't need to mock one of its methods).
+`MockFoo::Concrete()`. Perhaps you want to do it as part of a stub action, or
+perhaps your test doesn't need to mock `Concrete()` at all (but it would be
+oh-so painful to have to define a new mock class whenever you don't need to mock
+one of its methods).
-The trick is to leave a back door in your mock class for accessing the
-real methods in the base class:
+The trick is to leave a back door in your mock class for accessing the real
+methods in the base class:
```cpp
class MockFoo : public Foo {
public:
// Mocking a pure method.
- MOCK_METHOD1(Pure, void(int n));
+ MOCK_METHOD(void, Pure, (int n), (override));
// Mocking a concrete method. Foo::Concrete() is shadowed.
- MOCK_METHOD1(Concrete, int(const char* str));
+ MOCK_METHOD(int, Concrete, (const char* str), (override));
// Use this to call Concrete() defined in Foo.
int FooConcrete(const char* str) { return Foo::Concrete(str); }
@@ -604,30 +772,28 @@
Now, you can call `Foo::Concrete()` inside an action by:
```cpp
-using ::testing::_;
-using ::testing::Invoke;
...
- EXPECT_CALL(foo, Concrete(_))
- .WillOnce(Invoke(&foo, &MockFoo::FooConcrete));
+ EXPECT_CALL(foo, Concrete).WillOnce([&foo](const char* str) {
+ return foo.FooConcrete(str);
+ });
```
or tell the mock object that you don't want to mock `Concrete()`:
```cpp
-using ::testing::Invoke;
...
- ON_CALL(foo, Concrete(_))
- .WillByDefault(Invoke(&foo, &MockFoo::FooConcrete));
+ ON_CALL(foo, Concrete).WillByDefault([&foo](const char* str) {
+ return foo.FooConcrete(str);
+ });
```
-(Why don't we just write `Invoke(&foo, &Foo::Concrete)`? If you do
-that, `MockFoo::Concrete()` will be called (and cause an infinite
-recursion) since `Foo::Concrete()` is virtual. That's just how C++
-works.)
+(Why don't we just write `{ return foo.Concrete(str); }`? If you do that,
+`MockFoo::Concrete()` will be called (and cause an infinite recursion) since
+`Foo::Concrete()` is virtual. That's just how C++ works.)
-# Using Matchers #
+### Using Matchers
-## Matching Argument Values Exactly ##
+#### Matching Argument Values Exactly
You can specify exactly which arguments a mock method is expecting:
@@ -639,34 +805,30 @@
EXPECT_CALL(foo, DoThat("Hello", bar));
```
-## Using Simple Matchers ##
+#### Using Simple Matchers
You can use matchers to match arguments that have a certain property:
```cpp
-using ::testing::Ge;
using ::testing::NotNull;
using ::testing::Return;
...
EXPECT_CALL(foo, DoThis(Ge(5))) // The argument must be >= 5.
.WillOnce(Return('a'));
EXPECT_CALL(foo, DoThat("Hello", NotNull()));
- // The second argument must not be NULL.
+ // The second argument must not be NULL.
```
A frequently used matcher is `_`, which matches anything:
```cpp
-using ::testing::_;
-using ::testing::NotNull;
-...
EXPECT_CALL(foo, DoThat(_, NotNull()));
```
-## Combining Matchers ##
+#### Combining Matchers {#CombiningMatchers}
You can build complex matchers from existing ones using `AllOf()`,
-`AnyOf()`, and `Not()`:
+`AllOfArray()`, `AnyOf()`, `AnyOfArray()` and `Not()`:
```cpp
using ::testing::AllOf;
@@ -684,31 +846,32 @@
NULL));
```
-## Casting Matchers ##
+#### Casting Matchers {#SafeMatcherCast}
-Google Mock matchers are statically typed, meaning that the compiler
-can catch your mistake if you use a matcher of the wrong type (for
-example, if you use `Eq(5)` to match a `string` argument). Good for
-you!
+gMock matchers are statically typed, meaning that the compiler can catch your
+mistake if you use a matcher of the wrong type (for example, if you use `Eq(5)`
+to match a `string` argument). Good for you!
-Sometimes, however, you know what you're doing and want the compiler
-to give you some slack. One example is that you have a matcher for
-`long` and the argument you want to match is `int`. While the two
-types aren't exactly the same, there is nothing really wrong with
-using a `Matcher<long>` to match an `int` - after all, we can first
-convert the `int` argument to a `long` before giving it to the
-matcher.
+Sometimes, however, you know what you're doing and want the compiler to give you
+some slack. One example is that you have a matcher for `long` and the argument
+you want to match is `int`. While the two types aren't exactly the same, there
+is nothing really wrong with using a `Matcher<long>` to match an `int` - after
+all, we can first convert the `int` argument to a `long` losslessly before
+giving it to the matcher.
-To support this need, Google Mock gives you the
-`SafeMatcherCast<T>(m)` function. It casts a matcher `m` to type
-`Matcher<T>`. To ensure safety, Google Mock checks that (let `U` be the
-type `m` accepts):
+To support this need, gMock gives you the `SafeMatcherCast<T>(m)` function. It
+casts a matcher `m` to type `Matcher<T>`. To ensure safety, gMock checks that
+(let `U` be the type `m` accepts :
- 1. Type `T` can be implicitly cast to type `U`;
- 1. When both `T` and `U` are built-in arithmetic types (`bool`, integers, and floating-point numbers), the conversion from `T` to `U` is not lossy (in other words, any value representable by `T` can also be represented by `U`); and
- 1. When `U` is a reference, `T` must also be a reference (as the underlying matcher may be interested in the address of the `U` value).
+1. Type `T` can be *implicitly* cast to type `U`;
+2. When both `T` and `U` are built-in arithmetic types (`bool`, integers, and
+ floating-point numbers), the conversion from `T` to `U` is not lossy (in
+ other words, any value representable by `T` can also be represented by `U`);
+ and
+3. When `U` is a reference, `T` must also be a reference (as the underlying
+ matcher may be interested in the address of the `U` value).
-The code won't compile if any of these conditions aren't met.
+The code won't compile if any of these conditions isn't met.
Here's one example:
@@ -721,41 +884,41 @@
class MockFoo : public Foo {
public:
- MOCK_METHOD1(DoThis, void(Derived* derived));
+ MOCK_METHOD(void, DoThis, (Derived* derived), (override));
};
-...
+...
MockFoo foo;
// m is a Matcher<Base*> we got from somewhere.
EXPECT_CALL(foo, DoThis(SafeMatcherCast<Derived*>(m)));
```
-If you find `SafeMatcherCast<T>(m)` too limiting, you can use a similar
-function `MatcherCast<T>(m)`. The difference is that `MatcherCast` works
-as long as you can `static_cast` type `T` to type `U`.
+If you find `SafeMatcherCast<T>(m)` too limiting, you can use a similar function
+`MatcherCast<T>(m)`. The difference is that `MatcherCast` works as long as you
+can `static_cast` type `T` to type `U`.
-`MatcherCast` essentially lets you bypass C++'s type system
-(`static_cast` isn't always safe as it could throw away information,
-for example), so be careful not to misuse/abuse it.
+`MatcherCast` essentially lets you bypass C++'s type system (`static_cast` isn't
+always safe as it could throw away information, for example), so be careful not
+to misuse/abuse it.
-## Selecting Between Overloaded Functions ##
+#### Selecting Between Overloaded Functions {#SelectOverload}
-If you expect an overloaded function to be called, the compiler may
-need some help on which overloaded version it is.
+If you expect an overloaded function to be called, the compiler may need some
+help on which overloaded version it is.
-To disambiguate functions overloaded on the const-ness of this object,
-use the `Const()` argument wrapper.
+To disambiguate functions overloaded on the const-ness of this object, use the
+`Const()` argument wrapper.
```cpp
using ::testing::ReturnRef;
class MockFoo : public Foo {
...
- MOCK_METHOD0(GetBar, Bar&());
- MOCK_CONST_METHOD0(GetBar, const Bar&());
+ MOCK_METHOD(Bar&, GetBar, (), (override));
+ MOCK_METHOD(const Bar&, GetBar, (), (const, override));
};
-...
+...
MockFoo foo;
Bar bar1, bar2;
EXPECT_CALL(foo, GetBar()) // The non-const GetBar().
@@ -764,25 +927,22 @@
.WillOnce(ReturnRef(bar2));
```
-(`Const()` is defined by Google Mock and returns a `const` reference
-to its argument.)
+(`Const()` is defined by gMock and returns a `const` reference to its argument.)
-To disambiguate overloaded functions with the same number of arguments
-but different argument types, you may need to specify the exact type
-of a matcher, either by wrapping your matcher in `Matcher<type>()`, or
-using a matcher whose type is fixed (`TypedEq<type>`, `An<type>()`,
-etc):
+To disambiguate overloaded functions with the same number of arguments but
+different argument types, you may need to specify the exact type of a matcher,
+either by wrapping your matcher in `Matcher<type>()`, or using a matcher whose
+type is fixed (`TypedEq<type>`, `An<type>()`, etc):
```cpp
using ::testing::An;
-using ::testing::Lt;
using ::testing::Matcher;
using ::testing::TypedEq;
class MockPrinter : public Printer {
public:
- MOCK_METHOD1(Print, void(int n));
- MOCK_METHOD1(Print, void(char c));
+ MOCK_METHOD(void, Print, (int n), (override));
+ MOCK_METHOD(void, Print, (char c), (override));
};
TEST(PrinterTest, Print) {
@@ -798,12 +958,11 @@
}
```
-## Performing Different Actions Based on the Arguments ##
+#### Performing Different Actions Based on the Arguments
-When a mock method is called, the _last_ matching expectation that's
-still active will be selected (think "newer overrides older"). So, you
-can make a method do different things depending on its argument values
-like this:
+When a mock method is called, the *last* matching expectation that's still
+active will be selected (think "newer overrides older"). So, you can make a
+method do different things depending on its argument values like this:
```cpp
using ::testing::_;
@@ -813,44 +972,42 @@
// The default case.
EXPECT_CALL(foo, DoThis(_))
.WillRepeatedly(Return('b'));
-
// The more specific case.
EXPECT_CALL(foo, DoThis(Lt(5)))
.WillRepeatedly(Return('a'));
```
-Now, if `foo.DoThis()` is called with a value less than 5, `'a'` will
-be returned; otherwise `'b'` will be returned.
+Now, if `foo.DoThis()` is called with a value less than 5, `'a'` will be
+returned; otherwise `'b'` will be returned.
-## Matching Multiple Arguments as a Whole ##
+#### Matching Multiple Arguments as a Whole
-Sometimes it's not enough to match the arguments individually. For
-example, we may want to say that the first argument must be less than
-the second argument. The `With()` clause allows us to match
-all arguments of a mock function as a whole. For example,
+Sometimes it's not enough to match the arguments individually. For example, we
+may want to say that the first argument must be less than the second argument.
+The `With()` clause allows us to match all arguments of a mock function as a
+whole. For example,
```cpp
using ::testing::_;
-using ::testing::Lt;
using ::testing::Ne;
+using ::testing::Lt;
...
EXPECT_CALL(foo, InRange(Ne(0), _))
.With(Lt());
```
-says that the first argument of `InRange()` must not be 0, and must be
-less than the second argument.
+says that the first argument of `InRange()` must not be 0, and must be less than
+the second argument.
The expression inside `With()` must be a matcher of type
-`Matcher< ::testing::tuple<A1, ..., An> >`, where `A1`, ..., `An` are the
-types of the function arguments.
+`Matcher< ::std::tuple<A1, ..., An> >`, where `A1`, ..., `An` are the types of
+the function arguments.
-You can also write `AllArgs(m)` instead of `m` inside `.With()`. The
-two forms are equivalent, but `.With(AllArgs(Lt()))` is more readable
-than `.With(Lt())`.
+You can also write `AllArgs(m)` instead of `m` inside `.With()`. The two forms
+are equivalent, but `.With(AllArgs(Lt()))` is more readable than `.With(Lt())`.
-You can use `Args<k1, ..., kn>(m)` to match the `n` selected arguments
-(as a tuple) against `m`. For example,
+You can use `Args<k1, ..., kn>(m)` to match the `n` selected arguments (as a
+tuple) against `m`. For example,
```cpp
using ::testing::_;
@@ -858,65 +1015,73 @@
using ::testing::Args;
using ::testing::Lt;
...
- EXPECT_CALL(foo, Blah(_, _, _))
+ EXPECT_CALL(foo, Blah)
.With(AllOf(Args<0, 1>(Lt()), Args<1, 2>(Lt())));
```
-says that `Blah()` will be called with arguments `x`, `y`, and `z` where
-`x < y < z`.
+says that `Blah` will be called with arguments `x`, `y`, and `z` where `x < y <
+z`. Note that in this example, it wasn't necessary specify the positional
+matchers.
-As a convenience and example, Google Mock provides some matchers for
-2-tuples, including the `Lt()` matcher above. See the [CheatSheet](cheat_sheet.md) for
-the complete list.
+As a convenience and example, gMock provides some matchers for 2-tuples,
+including the `Lt()` matcher above. See [here](#MultiArgMatchers) for the
+complete list.
-Note that if you want to pass the arguments to a predicate of your own
-(e.g. `.With(Args<0, 1>(Truly(&MyPredicate)))`), that predicate MUST be
-written to take a `::testing::tuple` as its argument; Google Mock will pass the `n` selected arguments as _one_ single tuple to the predicate.
+Note that if you want to pass the arguments to a predicate of your own (e.g.
+`.With(Args<0, 1>(Truly(&MyPredicate)))`), that predicate MUST be written to
+take a `::std::tuple` as its argument; gMock will pass the `n` selected
+arguments as *one* single tuple to the predicate.
-## Using Matchers as Predicates ##
+#### Using Matchers as Predicates
-Have you noticed that a matcher is just a fancy predicate that also
-knows how to describe itself? Many existing algorithms take predicates
-as arguments (e.g. those defined in STL's `<algorithm>` header), and
-it would be a shame if Google Mock matchers are not allowed to
-participate.
+Have you noticed that a matcher is just a fancy predicate that also knows how to
+describe itself? Many existing algorithms take predicates as arguments (e.g.
+those defined in STL's `<algorithm>` header), and it would be a shame if gMock
+matchers are not allowed to participate.
-Luckily, you can use a matcher where a unary predicate functor is
-expected by wrapping it inside the `Matches()` function. For example,
+Luckily, you can use a matcher where a unary predicate functor is expected by
+wrapping it inside the `Matches()` function. For example,
```cpp
#include <algorithm>
#include <vector>
-std::vector<int> v;
+using ::testing::Matches;
+using ::testing::Ge;
+
+vector<int> v;
...
// How many elements in v are >= 10?
const int count = count_if(v.begin(), v.end(), Matches(Ge(10)));
```
-Since you can build complex matchers from simpler ones easily using
-Google Mock, this gives you a way to conveniently construct composite
-predicates (doing the same using STL's `<functional>` header is just
-painful). For example, here's a predicate that's satisfied by any
-number that is >= 0, <= 100, and != 50:
+Since you can build complex matchers from simpler ones easily using gMock, this
+gives you a way to conveniently construct composite predicates (doing the same
+using STL's `<functional>` header is just painful). For example, here's a
+predicate that's satisfied by any number that is >= 0, <= 100, and != 50:
```cpp
+using testing::AllOf;
+using testing::Ge;
+using testing::Le;
+using testing::Matches;
+using testing::Ne;
+...
Matches(AllOf(Ge(0), Le(100), Ne(50)))
```
-## Using Matchers in Google Test Assertions ##
+#### Using Matchers in googletest Assertions
Since matchers are basically predicates that also know how to describe
-themselves, there is a way to take advantage of them in
-[Google Test](../../googletest/) assertions. It's
-called `ASSERT_THAT` and `EXPECT_THAT`:
+themselves, there is a way to take advantage of them in googletest assertions.
+It's called `ASSERT_THAT` and `EXPECT_THAT`:
```cpp
ASSERT_THAT(value, matcher); // Asserts that value matches matcher.
EXPECT_THAT(value, matcher); // The non-fatal version.
```
-For example, in a Google Test test you can write:
+For example, in a googletest test you can write:
```cpp
#include "gmock/gmock.h"
@@ -926,75 +1091,94 @@
using ::testing::Le;
using ::testing::MatchesRegex;
using ::testing::StartsWith;
-...
+...
EXPECT_THAT(Foo(), StartsWith("Hello"));
EXPECT_THAT(Bar(), MatchesRegex("Line \\d+"));
ASSERT_THAT(Baz(), AllOf(Ge(5), Le(10)));
```
-which (as you can probably guess) executes `Foo()`, `Bar()`, and
-`Baz()`, and verifies that:
+which (as you can probably guess) executes `Foo()`, `Bar()`, and `Baz()`, and
+verifies that:
- * `Foo()` returns a string that starts with `"Hello"`.
- * `Bar()` returns a string that matches regular expression `"Line \\d+"`.
- * `Baz()` returns a number in the range [5, 10].
+* `Foo()` returns a string that starts with `"Hello"`.
+* `Bar()` returns a string that matches regular expression `"Line \\d+"`.
+* `Baz()` returns a number in the range [5, 10].
-The nice thing about these macros is that _they read like
-English_. They generate informative messages too. For example, if the
-first `EXPECT_THAT()` above fails, the message will be something like:
+The nice thing about these macros is that *they read like English*. They
+generate informative messages too. For example, if the first `EXPECT_THAT()`
+above fails, the message will be something like:
-```
+```cpp
Value of: Foo()
Actual: "Hi, world!"
Expected: starts with "Hello"
```
-**Credit:** The idea of `(ASSERT|EXPECT)_THAT` was stolen from the
-[Hamcrest](https://github.com/hamcrest/) project, which adds
-`assertThat()` to JUnit.
+**Credit:** The idea of `(ASSERT|EXPECT)_THAT` was borrowed from Joe Walnes'
+Hamcrest project, which adds `assertThat()` to JUnit.
-## Using Predicates as Matchers ##
+#### Using Predicates as Matchers
-Google Mock provides a built-in set of matchers. In case you find them
-lacking, you can use an arbitray unary predicate function or functor
-as a matcher - as long as the predicate accepts a value of the type
-you want. You do this by wrapping the predicate inside the `Truly()`
-function, for example:
+gMock provides a [built-in set](#MatcherList) of matchers. In case you find them
+lacking, you can use an arbitrary unary predicate function or functor as a
+matcher - as long as the predicate accepts a value of the type you want. You do
+this by wrapping the predicate inside the `Truly()` function, for example:
```cpp
using ::testing::Truly;
int IsEven(int n) { return (n % 2) == 0 ? 1 : 0; }
...
-
// Bar() must be called with an even number.
EXPECT_CALL(foo, Bar(Truly(IsEven)));
```
-Note that the predicate function / functor doesn't have to return
-`bool`. It works as long as the return value can be used as the
-condition in statement `if (condition) ...`.
+Note that the predicate function / functor doesn't have to return `bool`. It
+works as long as the return value can be used as the condition in in statement
+`if (condition) ...`.
-## Matching Arguments that Are Not Copyable ##
+#### Using Callbacks as Matchers
-When you do an `EXPECT_CALL(mock_obj, Foo(bar))`, Google Mock saves
-away a copy of `bar`. When `Foo()` is called later, Google Mock
-compares the argument to `Foo()` with the saved copy of `bar`. This
-way, you don't need to worry about `bar` being modified or destroyed
-after the `EXPECT_CALL()` is executed. The same is true when you use
-matchers like `Eq(bar)`, `Le(bar)`, and so on.
+Callbacks are widely used in `google3`. Conceptually, a `ResultCallback1<bool,
+T>` is just a predicate on argument of type `T`. Naturally, we sometimes would
+want to use such a callback as a matcher.
-But what if `bar` cannot be copied (i.e. has no copy constructor)? You
-could define your own matcher function and use it with `Truly()`, as
-the previous couple of recipes have shown. Or, you may be able to get
-away from it if you can guarantee that `bar` won't be changed after
-the `EXPECT_CALL()` is executed. Just tell Google Mock that it should
-save a reference to `bar`, instead of a copy of it. Here's how:
+gMock gives you two function templates in namespace `testing` to turn callbacks
+into matchers.
+
+The first is `Truly(callback)`. It matches `argument` iff
+`callback->Run(argument)` returns `true`.
+
+The second is `AddressSatisfies(callback)`, which matches `argument` whenever
+`callback->Run(&argument)` returns `true`.
+
+The callbacks used in `Truly()` and `AddressSatisfies()` must be permanent (e.g.
+those returned by `NewPermanentCallback()`), or you'll get a run-time error. The
+matcher takes ownership of the callback, so you don't need to worry about
+deleting it.
+
+For examples, see
+google3/testing/base/internal/gmock_utils/callback-matchers_test.cc.
+
+#### Matching Arguments that Are Not Copyable
+
+When you do an `EXPECT_CALL(mock_obj, Foo(bar))`, gMock saves away a copy of
+`bar`. When `Foo()` is called later, gMock compares the argument to `Foo()` with
+the saved copy of `bar`. This way, you don't need to worry about `bar` being
+modified or destroyed after the `EXPECT_CALL()` is executed. The same is true
+when you use matchers like `Eq(bar)`, `Le(bar)`, and so on.
+
+But what if `bar` cannot be copied (i.e. has no copy constructor)? You could
+define your own matcher function or callback and use it with `Truly()`, as the
+previous couple of recipes have shown. Or, you may be able to get away from it
+if you can guarantee that `bar` won't be changed after the `EXPECT_CALL()` is
+executed. Just tell gMock that it should save a reference to `bar`, instead of a
+copy of it. Here's how:
```cpp
-using ::testing::Eq;
using ::testing::ByRef;
+using ::testing::Eq;
using ::testing::Lt;
...
// Expects that Foo()'s argument == bar.
@@ -1004,65 +1188,85 @@
EXPECT_CALL(mock_obj, Foo(Lt(ByRef(bar))));
```
-Remember: if you do this, don't change `bar` after the
-`EXPECT_CALL()`, or the result is undefined.
+Remember: if you do this, don't change `bar` after the `EXPECT_CALL()`, or the
+result is undefined.
-## Validating a Member of an Object ##
+#### Validating a Member of an Object
-Often a mock function takes a reference to object as an argument. When
-matching the argument, you may not want to compare the entire object
-against a fixed object, as that may be over-specification. Instead,
-you may need to validate a certain member variable or the result of a
-certain getter method of the object. You can do this with `Field()`
-and `Property()`. More specifically,
+Often a mock function takes a reference to object as an argument. When matching
+the argument, you may not want to compare the entire object against a fixed
+object, as that may be over-specification. Instead, you may need to validate a
+certain member variable or the result of a certain getter method of the object.
+You can do this with `Field()` and `Property()`. More specifically,
```cpp
Field(&Foo::bar, m)
```
-is a matcher that matches a `Foo` object whose `bar` member variable
-satisfies matcher `m`.
+is a matcher that matches a `Foo` object whose `bar` member variable satisfies
+matcher `m`.
```cpp
Property(&Foo::baz, m)
```
-is a matcher that matches a `Foo` object whose `baz()` method returns
-a value that satisfies matcher `m`.
+is a matcher that matches a `Foo` object whose `baz()` method returns a value
+that satisfies matcher `m`.
For example:
-| Expression | Description |
-|:-----------------------------|:-----------------------------------|
-| `Field(&Foo::number, Ge(3))` | Matches `x` where `x.number >= 3`. |
-| `Property(&Foo::name, StartsWith("John "))` | Matches `x` where `x.name()` starts with `"John "`. |
+| Expression | Description |
+| :--------------------------- | :--------------------------------------- |
+| `Field(&Foo::number, Ge(3))` | Matches `x` where `x.number >= 3`. |
+| `Property(&Foo::name, | Matches `x` where `x.name()` starts with |
+: StartsWith("John "))` : `"John "`. :
-Note that in `Property(&Foo::baz, ...)`, method `baz()` must take no
-argument and be declared as `const`.
+Note that in `Property(&Foo::baz, ...)`, method `baz()` must take no argument
+and be declared as `const`.
-BTW, `Field()` and `Property()` can also match plain pointers to
-objects. For instance,
+BTW, `Field()` and `Property()` can also match plain pointers to objects. For
+instance,
```cpp
+using ::testing::Field;
+using ::testing::Ge;
+...
Field(&Foo::number, Ge(3))
```
-matches a plain pointer `p` where `p->number >= 3`. If `p` is `NULL`,
-the match will always fail regardless of the inner matcher.
+matches a plain pointer `p` where `p->number >= 3`. If `p` is `NULL`, the match
+will always fail regardless of the inner matcher.
-What if you want to validate more than one members at the same time?
-Remember that there is `AllOf()`.
+What if you want to validate more than one members at the same time? Remember
+that there are [`AllOf()` and `AllOfArray()`](#CombiningMatchers).
-## Validating the Value Pointed to by a Pointer Argument ##
+Finally `Field()` and `Property()` provide overloads that take the field or
+property names as the first argument to include it in the error message. This
+can be useful when creating combined matchers.
-C++ functions often take pointers as arguments. You can use matchers
-like `IsNull()`, `NotNull()`, and other comparison matchers to match a
-pointer, but what if you want to make sure the value _pointed to_ by
-the pointer, instead of the pointer itself, has a certain property?
-Well, you can use the `Pointee(m)` matcher.
+```cpp
+using ::testing::AllOf;
+using ::testing::Field;
+using ::testing::Matcher;
+using ::testing::SafeMatcherCast;
-`Pointee(m)` matches a pointer iff `m` matches the value the pointer
-points to. For example:
+Matcher<Foo> IsFoo(const Foo& foo) {
+ return AllOf(Field("some_field", &Foo::some_field, foo.some_field),
+ Field("other_field", &Foo::other_field, foo.other_field),
+ Field("last_field", &Foo::last_field, foo.last_field));
+}
+```
+
+#### Validating the Value Pointed to by a Pointer Argument
+
+C++ functions often take pointers as arguments. You can use matchers like
+`IsNull()`, `NotNull()`, and other comparison matchers to match a pointer, but
+what if you want to make sure the value *pointed to* by the pointer, instead of
+the pointer itself, has a certain property? Well, you can use the `Pointee(m)`
+matcher.
+
+`Pointee(m)` matches a pointer iff `m` matches the value the pointer points to.
+For example:
```cpp
using ::testing::Ge;
@@ -1071,40 +1275,44 @@
EXPECT_CALL(foo, Bar(Pointee(Ge(3))));
```
-expects `foo.Bar()` to be called with a pointer that points to a value
-greater than or equal to 3.
+expects `foo.Bar()` to be called with a pointer that points to a value greater
+than or equal to 3.
-One nice thing about `Pointee()` is that it treats a `NULL` pointer as
-a match failure, so you can write `Pointee(m)` instead of
+One nice thing about `Pointee()` is that it treats a `NULL` pointer as a match
+failure, so you can write `Pointee(m)` instead of
```cpp
+using ::testing::AllOf;
+using ::testing::NotNull;
+using ::testing::Pointee;
+...
AllOf(NotNull(), Pointee(m))
```
without worrying that a `NULL` pointer will crash your test.
-Also, did we tell you that `Pointee()` works with both raw pointers
-**and** smart pointers (`linked_ptr`, `shared_ptr`, `scoped_ptr`, and
-etc)?
+Also, did we tell you that `Pointee()` works with both raw pointers **and**
+smart pointers (`std::unique_ptr`, `std::shared_ptr`, etc)?
-What if you have a pointer to pointer? You guessed it - you can use
-nested `Pointee()` to probe deeper inside the value. For example,
-`Pointee(Pointee(Lt(3)))` matches a pointer that points to a pointer
-that points to a number less than 3 (what a mouthful...).
+What if you have a pointer to pointer? You guessed it - you can use nested
+`Pointee()` to probe deeper inside the value. For example,
+`Pointee(Pointee(Lt(3)))` matches a pointer that points to a pointer that points
+to a number less than 3 (what a mouthful...).
-## Testing a Certain Property of an Object ##
+#### Testing a Certain Property of an Object
-Sometimes you want to specify that an object argument has a certain
-property, but there is no existing matcher that does this. If you want
-good error messages, you should define a matcher. If you want to do it
+Sometimes you want to specify that an object argument has a certain property,
+but there is no existing matcher that does this. If you want good error
+messages, you should [define a matcher](#NewMatchers). If you want to do it
quick and dirty, you could get away with writing an ordinary function.
-Let's say you have a mock function that takes an object of type `Foo`,
-which has an `int bar()` method and an `int baz()` method, and you
-want to constrain that the argument's `bar()` value plus its `baz()`
-value is a given number. Here's how you can define a matcher to do it:
+Let's say you have a mock function that takes an object of type `Foo`, which has
+an `int bar()` method and an `int baz()` method, and you want to constrain that
+the argument's `bar()` value plus its `baz()` value is a given number. Here's
+how you can define a matcher to do it:
```cpp
+using ::testing::Matcher;
using ::testing::MatcherInterface;
using ::testing::MatchResultListener;
@@ -1113,62 +1321,58 @@
explicit BarPlusBazEqMatcher(int expected_sum)
: expected_sum_(expected_sum) {}
- virtual bool MatchAndExplain(const Foo& foo,
- MatchResultListener* listener) const {
+ bool MatchAndExplain(const Foo& foo,
+ MatchResultListener* /* listener */) const override {
return (foo.bar() + foo.baz()) == expected_sum_;
}
- virtual void DescribeTo(::std::ostream* os) const {
+ void DescribeTo(::std::ostream* os) const override {
*os << "bar() + baz() equals " << expected_sum_;
}
- virtual void DescribeNegationTo(::std::ostream* os) const {
+ void DescribeNegationTo(::std::ostream* os) const override {
*os << "bar() + baz() does not equal " << expected_sum_;
}
private:
const int expected_sum_;
};
-inline Matcher<const Foo&> BarPlusBazEq(int expected_sum) {
+Matcher<const Foo&> BarPlusBazEq(int expected_sum) {
return MakeMatcher(new BarPlusBazEqMatcher(expected_sum));
}
...
-
EXPECT_CALL(..., DoThis(BarPlusBazEq(5)))...;
```
-## Matching Containers ##
+#### Matching Containers
-Sometimes an STL container (e.g. list, vector, map, ...) is passed to
-a mock function and you may want to validate it. Since most STL
-containers support the `==` operator, you can write
-`Eq(expected_container)` or simply `expected_container` to match a
-container exactly.
+Sometimes an STL container (e.g. list, vector, map, ...) is passed to a mock
+function and you may want to validate it. Since most STL containers support the
+`==` operator, you can write `Eq(expected_container)` or simply
+`expected_container` to match a container exactly.
-Sometimes, though, you may want to be more flexible (for example, the
-first element must be an exact match, but the second element can be
-any positive number, and so on). Also, containers used in tests often
-have a small number of elements, and having to define the expected
-container out-of-line is a bit of a hassle.
+Sometimes, though, you may want to be more flexible (for example, the first
+element must be an exact match, but the second element can be any positive
+number, and so on). Also, containers used in tests often have a small number of
+elements, and having to define the expected container out-of-line is a bit of a
+hassle.
-You can use the `ElementsAre()` or `UnorderedElementsAre()` matcher in
-such cases:
+You can use the `ElementsAre()` or `UnorderedElementsAre()` matcher in such
+cases:
```cpp
using ::testing::_;
using ::testing::ElementsAre;
using ::testing::Gt;
...
-
- MOCK_METHOD1(Foo, void(const vector<int>& numbers));
+ MOCK_METHOD(void, Foo, (const vector<int>& numbers), (override));
...
-
EXPECT_CALL(mock, Foo(ElementsAre(1, Gt(0), _, 5)));
```
-The above matcher says that the container must have 4 elements, which
-must be 1, greater than 0, anything, and 5 respectively.
+The above matcher says that the container must have 4 elements, which must be 1,
+greater than 0, anything, and 5 respectively.
If you instead write:
@@ -1177,37 +1381,32 @@
using ::testing::Gt;
using ::testing::UnorderedElementsAre;
...
-
- MOCK_METHOD1(Foo, void(const vector<int>& numbers));
+ MOCK_METHOD(void, Foo, (const vector<int>& numbers), (override));
...
-
EXPECT_CALL(mock, Foo(UnorderedElementsAre(1, Gt(0), _, 5)));
```
-It means that the container must have 4 elements, which under some
-permutation must be 1, greater than 0, anything, and 5 respectively.
+It means that the container must have 4 elements, which (under some permutation)
+must be 1, greater than 0, anything, and 5 respectively.
-`ElementsAre()` and `UnorderedElementsAre()` are overloaded to take 0
-to 10 arguments. If more are needed, you can place them in a C-style
-array and use `ElementsAreArray()` or `UnorderedElementsAreArray()`
-instead:
+As an alternative you can place the arguments in a C-style array and use
+`ElementsAreArray()` or `UnorderedElementsAreArray()` instead:
```cpp
using ::testing::ElementsAreArray;
...
-
// ElementsAreArray accepts an array of element values.
- const int expected_vector1[] = { 1, 5, 2, 4, ... };
+ const int expected_vector1[] = {1, 5, 2, 4, ...};
EXPECT_CALL(mock, Foo(ElementsAreArray(expected_vector1)));
// Or, an array of element matchers.
- Matcher<int> expected_vector2 = { 1, Gt(2), _, 3, ... };
+ Matcher<int> expected_vector2[] = {1, Gt(2), _, 3, ...};
EXPECT_CALL(mock, Foo(ElementsAreArray(expected_vector2)));
```
-In case the array needs to be dynamically created (and therefore the
-array size cannot be inferred by the compiler), you can give
-`ElementsAreArray()` an additional argument to specify the array size:
+In case the array needs to be dynamically created (and therefore the array size
+cannot be inferred by the compiler), you can give `ElementsAreArray()` an
+additional argument to specify the array size:
```cpp
using ::testing::ElementsAreArray;
@@ -1217,65 +1416,133 @@
EXPECT_CALL(mock, Foo(ElementsAreArray(expected_vector3, count)));
```
-**Tips:**
-
- * `ElementsAre*()` can be used to match _any_ container that implements the STL iterator pattern (i.e. it has a `const_iterator` type and supports `begin()/end()`), not just the ones defined in STL. It will even work with container types yet to be written - as long as they follows the above pattern.
- * You can use nested `ElementsAre*()` to match nested (multi-dimensional) containers.
- * If the container is passed by pointer instead of by reference, just write `Pointee(ElementsAre*(...))`.
- * The order of elements _matters_ for `ElementsAre*()`. Therefore don't use it with containers whose element order is undefined (e.g. `hash_map`).
-
-## Sharing Matchers ##
-
-Under the hood, a Google Mock matcher object consists of a pointer to
-a ref-counted implementation object. Copying matchers is allowed and
-very efficient, as only the pointer is copied. When the last matcher
-that references the implementation object dies, the implementation
-object will be deleted.
-
-Therefore, if you have some complex matcher that you want to use again
-and again, there is no need to build it every time. Just assign it to a
-matcher variable and use that variable repeatedly! For example,
+Use `Pair` when comparing maps or other associative containers.
```cpp
+using testing::ElementsAre;
+using testing::Pair;
+...
+ std::map<string, int> m = {{"a", 1}, {"b", 2}, {"c", 3}};
+ EXPECT_THAT(m, ElementsAre(Pair("a", 1), Pair("b", 2), Pair("c", 3)));
+```
+
+**Tips:**
+
+* `ElementsAre*()` can be used to match *any* container that implements the
+ STL iterator pattern (i.e. it has a `const_iterator` type and supports
+ `begin()/end()`), not just the ones defined in STL. It will even work with
+ container types yet to be written - as long as they follows the above
+ pattern.
+* You can use nested `ElementsAre*()` to match nested (multi-dimensional)
+ containers.
+* If the container is passed by pointer instead of by reference, just write
+ `Pointee(ElementsAre*(...))`.
+* The order of elements *matters* for `ElementsAre*()`. If you are using it
+ with containers whose element order are undefined (e.g. `hash_map`) you
+ should use `WhenSorted` around `ElementsAre`.
+
+#### Sharing Matchers
+
+Under the hood, a gMock matcher object consists of a pointer to a ref-counted
+implementation object. Copying matchers is allowed and very efficient, as only
+the pointer is copied. When the last matcher that references the implementation
+object dies, the implementation object will be deleted.
+
+Therefore, if you have some complex matcher that you want to use again and
+again, there is no need to build it everytime. Just assign it to a matcher
+variable and use that variable repeatedly! For example,
+
+```cpp
+using ::testing::AllOf;
+using ::testing::Gt;
+using ::testing::Le;
+using ::testing::Matcher;
+...
Matcher<int> in_range = AllOf(Gt(5), Le(10));
... use in_range as a matcher in multiple EXPECT_CALLs ...
```
-# Setting Expectations #
+#### Matchers must have no side-effects {#PureMatchers}
-## Knowing When to Expect ##
+WARNING: gMock does not guarantee when or how many times a matcher will be
+invoked. Therefore, all matchers must be *purely functional*: they cannot have
+any side effects, and the match result must not depend on anything other than
+the matcher's parameters and the value being matched.
-`ON_CALL` is likely the single most under-utilized construct in Google Mock.
+This requirement must be satisfied no matter how a matcher is defined (e.g., if
+it is one of the standard matchers, or a custom matcher). In particular, a
+matcher can never call a mock function, as that will affect the state of the
+mock object and gMock.
-There are basically two constructs for defining the behavior of a mock object: `ON_CALL` and `EXPECT_CALL`. The difference? `ON_CALL` defines what happens when a mock method is called, but _doesn't imply any expectation on the method being called._ `EXPECT_CALL` not only defines the behavior, but also sets an expectation that _the method will be called with the given arguments, for the given number of times_ (and _in the given order_ when you specify the order too).
+### Setting Expectations
-Since `EXPECT_CALL` does more, isn't it better than `ON_CALL`? Not really. Every `EXPECT_CALL` adds a constraint on the behavior of the code under test. Having more constraints than necessary is _baaad_ - even worse than not having enough constraints.
+#### Knowing When to Expect {#UseOnCall}
-This may be counter-intuitive. How could tests that verify more be worse than tests that verify less? Isn't verification the whole point of tests?
+<!-- GOOGLETEST_CM0018 DO NOT DELETE -->
-The answer, lies in _what_ a test should verify. **A good test verifies the contract of the code.** If a test over-specifies, it doesn't leave enough freedom to the implementation. As a result, changing the implementation without breaking the contract (e.g. refactoring and optimization), which should be perfectly fine to do, can break such tests. Then you have to spend time fixing them, only to see them broken again the next time the implementation is changed.
+**`ON_CALL`** is likely the *single most under-utilized construct* in gMock.
-Keep in mind that one doesn't have to verify more than one property in one test. In fact, **it's a good style to verify only one thing in one test.** If you do that, a bug will likely break only one or two tests instead of dozens (which case would you rather debug?). If you are also in the habit of giving tests descriptive names that tell what they verify, you can often easily guess what's wrong just from the test log itself.
+There are basically two constructs for defining the behavior of a mock object:
+`ON_CALL` and `EXPECT_CALL`. The difference? `ON_CALL` defines what happens when
+a mock method is called, but <em>doesn't imply any expectation on the method
+being called</em>. `EXPECT_CALL` not only defines the behavior, but also sets an
+expectation that <em>the method will be called with the given arguments, for the
+given number of times</em> (and *in the given order* when you specify the order
+too).
-So use `ON_CALL` by default, and only use `EXPECT_CALL` when you actually intend to verify that the call is made. For example, you may have a bunch of `ON_CALL`s in your test fixture to set the common mock behavior shared by all tests in the same group, and write (scarcely) different `EXPECT_CALL`s in different `TEST_F`s to verify different aspects of the code's behavior. Compared with the style where each `TEST` has many `EXPECT_CALL`s, this leads to tests that are more resilient to implementational changes (and thus less likely to require maintenance) and makes the intent of the tests more obvious (so they are easier to maintain when you do need to maintain them).
+Since `EXPECT_CALL` does more, isn't it better than `ON_CALL`? Not really. Every
+`EXPECT_CALL` adds a constraint on the behavior of the code under test. Having
+more constraints than necessary is *baaad* - even worse than not having enough
+constraints.
-If you are bothered by the "Uninteresting mock function call" message printed when a mock method without an `EXPECT_CALL` is called, you may use a `NiceMock` instead to suppress all such messages for the mock object, or suppress the message for specific methods by adding `EXPECT_CALL(...).Times(AnyNumber())`. DO NOT suppress it by blindly adding an `EXPECT_CALL(...)`, or you'll have a test that's a pain to maintain.
+This may be counter-intuitive. How could tests that verify more be worse than
+tests that verify less? Isn't verification the whole point of tests?
-## Ignoring Uninteresting Calls ##
+The answer lies in *what* a test should verify. **A good test verifies the
+contract of the code.** If a test over-specifies, it doesn't leave enough
+freedom to the implementation. As a result, changing the implementation without
+breaking the contract (e.g. refactoring and optimization), which should be
+perfectly fine to do, can break such tests. Then you have to spend time fixing
+them, only to see them broken again the next time the implementation is changed.
-If you are not interested in how a mock method is called, just don't
-say anything about it. In this case, if the method is ever called,
-Google Mock will perform its default action to allow the test program
-to continue. If you are not happy with the default action taken by
-Google Mock, you can override it using `DefaultValue<T>::Set()`
-(described later in this document) or `ON_CALL()`.
+Keep in mind that one doesn't have to verify more than one property in one test.
+In fact, **it's a good style to verify only one thing in one test.** If you do
+that, a bug will likely break only one or two tests instead of dozens (which
+case would you rather debug?). If you are also in the habit of giving tests
+descriptive names that tell what they verify, you can often easily guess what's
+wrong just from the test log itself.
-Please note that once you expressed interest in a particular mock
-method (via `EXPECT_CALL()`), all invocations to it must match some
-expectation. If this function is called but the arguments don't match
-any `EXPECT_CALL()` statement, it will be an error.
+So use `ON_CALL` by default, and only use `EXPECT_CALL` when you actually intend
+to verify that the call is made. For example, you may have a bunch of `ON_CALL`s
+in your test fixture to set the common mock behavior shared by all tests in the
+same group, and write (scarcely) different `EXPECT_CALL`s in different `TEST_F`s
+to verify different aspects of the code's behavior. Compared with the style
+where each `TEST` has many `EXPECT_CALL`s, this leads to tests that are more
+resilient to implementational changes (and thus less likely to require
+maintenance) and makes the intent of the tests more obvious (so they are easier
+to maintain when you do need to maintain them).
-## Disallowing Unexpected Calls ##
+If you are bothered by the "Uninteresting mock function call" message printed
+when a mock method without an `EXPECT_CALL` is called, you may use a `NiceMock`
+instead to suppress all such messages for the mock object, or suppress the
+message for specific methods by adding `EXPECT_CALL(...).Times(AnyNumber())`. DO
+NOT suppress it by blindly adding an `EXPECT_CALL(...)`, or you'll have a test
+that's a pain to maintain.
+
+#### Ignoring Uninteresting Calls
+
+If you are not interested in how a mock method is called, just don't say
+anything about it. In this case, if the method is ever called, gMock will
+perform its default action to allow the test program to continue. If you are not
+happy with the default action taken by gMock, you can override it using
+`DefaultValue<T>::Set()` (described [here](#DefaultValue)) or `ON_CALL()`.
+
+Please note that once you expressed interest in a particular mock method (via
+`EXPECT_CALL()`), all invocations to it must match some expectation. If this
+function is called but the arguments don't match any `EXPECT_CALL()` statement,
+it will be an error.
+
+#### Disallowing Unexpected Calls
If a mock method shouldn't be called at all, explicitly say so:
@@ -1286,8 +1553,8 @@
.Times(0);
```
-If some calls to the method are allowed, but the rest are not, just
-list all the expected calls:
+If some calls to the method are allowed, but the rest are not, just list all the
+expected calls:
```cpp
using ::testing::AnyNumber;
@@ -1298,26 +1565,44 @@
.Times(AnyNumber());
```
-A call to `foo.Bar()` that doesn't match any of the `EXPECT_CALL()`
-statements will be an error.
+A call to `foo.Bar()` that doesn't match any of the `EXPECT_CALL()` statements
+will be an error.
-## Understanding Uninteresting vs Unexpected Calls ##
+#### Understanding Uninteresting vs Unexpected Calls {#uninteresting-vs-unexpected}
-_Uninteresting_ calls and _unexpected_ calls are different concepts in Google Mock. _Very_ different.
+*Uninteresting* calls and *unexpected* calls are different concepts in gMock.
+*Very* different.
-A call `x.Y(...)` is **uninteresting** if there's _not even a single_ `EXPECT_CALL(x, Y(...))` set. In other words, the test isn't interested in the `x.Y()` method at all, as evident in that the test doesn't care to say anything about it.
+A call `x.Y(...)` is **uninteresting** if there's *not even a single*
+`EXPECT_CALL(x, Y(...))` set. In other words, the test isn't interested in the
+`x.Y()` method at all, as evident in that the test doesn't care to say anything
+about it.
-A call `x.Y(...)` is **unexpected** if there are some `EXPECT_CALL(x, Y(...))s` set, but none of them matches the call. Put another way, the test is interested in the `x.Y()` method (therefore it _explicitly_ sets some `EXPECT_CALL` to verify how it's called); however, the verification fails as the test doesn't expect this particular call to happen.
+A call `x.Y(...)` is **unexpected** if there are *some* `EXPECT_CALL(x,
+Y(...))`s set, but none of them matches the call. Put another way, the test is
+interested in the `x.Y()` method (therefore it explicitly sets some
+`EXPECT_CALL` to verify how it's called); however, the verification fails as the
+test doesn't expect this particular call to happen.
-**An unexpected call is always an error,** as the code under test doesn't behave the way the test expects it to behave.
+**An unexpected call is always an error,** as the code under test doesn't behave
+the way the test expects it to behave.
-**By default, an uninteresting call is not an error,** as it violates no constraint specified by the test. (Google Mock's philosophy is that saying nothing means there is no constraint.) However, it leads to a warning, as it _might_ indicate a problem (e.g. the test author might have forgotten to specify a constraint).
+**By default, an uninteresting call is not an error,** as it violates no
+constraint specified by the test. (gMock's philosophy is that saying nothing
+means there is no constraint.) However, it leads to a warning, as it *might*
+indicate a problem (e.g. the test author might have forgotten to specify a
+constraint).
-In Google Mock, `NiceMock` and `StrictMock` can be used to make a mock class "nice" or "strict". How does this affect uninteresting calls and unexpected calls?
+In gMock, `NiceMock` and `StrictMock` can be used to make a mock class "nice" or
+"strict". How does this affect uninteresting calls and unexpected calls?
-A **nice mock** suppresses uninteresting call warnings. It is less chatty than the default mock, but otherwise is the same. If a test fails with a default mock, it will also fail using a nice mock instead. And vice versa. Don't expect making a mock nice to change the test's result.
+A **nice mock** suppresses uninteresting call *warnings*. It is less chatty than
+the default mock, but otherwise is the same. If a test fails with a default
+mock, it will also fail using a nice mock instead. And vice versa. Don't expect
+making a mock nice to change the test's result.
-A **strict mock** turns uninteresting call warnings into errors. So making a mock strict may change the test's result.
+A **strict mock** turns uninteresting call warnings into errors. So making a
+mock strict may change the test's result.
Let's look at an example:
@@ -1332,9 +1617,13 @@
}
```
-The sole `EXPECT_CALL` here says that all calls to `GetDomainOwner()` must have `"google.com"` as the argument. If `GetDomainOwner("yahoo.com")` is called, it will be an unexpected call, and thus an error. Having a nice mock doesn't change the severity of an unexpected call.
+The sole `EXPECT_CALL` here says that all calls to `GetDomainOwner()` must have
+`"google.com"` as the argument. If `GetDomainOwner("yahoo.com")` is called, it
+will be an unexpected call, and thus an error. *Having a nice mock doesn't
+change the severity of an unexpected call.*
-So how do we tell Google Mock that `GetDomainOwner()` can be called with some other arguments as well? The standard technique is to add a "catch all" `EXPECT_CALL`:
+So how do we tell gMock that `GetDomainOwner()` can be called with some other
+arguments as well? The standard technique is to add a "catch all" `EXPECT_CALL`:
```cpp
EXPECT_CALL(mock_registry, GetDomainOwner(_))
@@ -1343,28 +1632,58 @@
.WillRepeatedly(Return("Larry Page"));
```
-Remember that `_` is the wildcard matcher that matches anything. With this, if `GetDomainOwner("google.com")` is called, it will do what the second `EXPECT_CALL` says; if it is called with a different argument, it will do what the first `EXPECT_CALL` says.
+Remember that `_` is the wildcard matcher that matches anything. With this, if
+`GetDomainOwner("google.com")` is called, it will do what the second
+`EXPECT_CALL` says; if it is called with a different argument, it will do what
+the first `EXPECT_CALL` says.
-Note that the order of the two `EXPECT_CALLs` is important, as a newer `EXPECT_CALL` takes precedence over an older one.
+Note that the order of the two `EXPECT_CALL`s is important, as a newer
+`EXPECT_CALL` takes precedence over an older one.
-For more on uninteresting calls, nice mocks, and strict mocks, read ["The Nice, the Strict, and the Naggy"](#the-nice-the-strict-and-the-naggy).
+For more on uninteresting calls, nice mocks, and strict mocks, read
+["The Nice, the Strict, and the Naggy"](#NiceStrictNaggy).
-## Expecting Ordered Calls ##
+#### Ignoring Uninteresting Arguments {#ParameterlessExpectations}
-Although an `EXPECT_CALL()` statement defined earlier takes precedence
-when Google Mock tries to match a function call with an expectation,
-by default calls don't have to happen in the order `EXPECT_CALL()`
-statements are written. For example, if the arguments match the
-matchers in the third `EXPECT_CALL()`, but not those in the first two,
-then the third expectation will be used.
-
-If you would rather have all calls occur in the order of the
-expectations, put the `EXPECT_CALL()` statements in a block where you
-define a variable of type `InSequence`:
+If your test doesn't care about the parameters (it only cares about the number
+or order of calls), you can often simply omit the parameter list:
```cpp
- using ::testing::_;
- using ::testing::InSequence;
+ // Expect foo.Bar( ... ) twice with any arguments.
+ EXPECT_CALL(foo, Bar).Times(2);
+
+ // Delegate to the given method whenever the factory is invoked.
+ ON_CALL(foo_factory, MakeFoo)
+ .WillByDefault(&BuildFooForTest);
+```
+
+This functionality is only available when a method is not overloaded; to prevent
+unexpected behavior it is a compilation error to try to set an expectation on a
+method where the specific overload is ambiguous. You can work around this by
+supplying a [simpler mock interface](#SimplerInterfaces) than the mocked class
+provides.
+
+This pattern is also useful when the arguments are interesting, but match logic
+is substantially complex. You can leave the argument list unspecified and use
+SaveArg actions to [save the values for later verification](#SaveArgVerify). If
+you do that, you can easily differentiate calling the method the wrong number of
+times from calling it with the wrong arguments.
+
+#### Expecting Ordered Calls {#OrderedCalls}
+
+Although an `EXPECT_CALL()` statement defined earlier takes precedence when
+gMock tries to match a function call with an expectation, by default calls don't
+have to happen in the order `EXPECT_CALL()` statements are written. For example,
+if the arguments match the matchers in the third `EXPECT_CALL()`, but not those
+in the first two, then the third expectation will be used.
+
+If you would rather have all calls occur in the order of the expectations, put
+the `EXPECT_CALL()` statements in a block where you define a variable of type
+`InSequence`:
+
+```cpp
+using ::testing::_;
+using ::testing::InSequence;
{
InSequence s;
@@ -1376,46 +1695,44 @@
}
```
-In this example, we expect a call to `foo.DoThis(5)`, followed by two
-calls to `bar.DoThat()` where the argument can be anything, which are
-in turn followed by a call to `foo.DoThis(6)`. If a call occurred
-out-of-order, Google Mock will report an error.
+In this example, we expect a call to `foo.DoThis(5)`, followed by two calls to
+`bar.DoThat()` where the argument can be anything, which are in turn followed by
+a call to `foo.DoThis(6)`. If a call occurred out-of-order, gMock will report an
+error.
-## Expecting Partially Ordered Calls ##
+#### Expecting Partially Ordered Calls {#PartialOrder}
-Sometimes requiring everything to occur in a predetermined order can
-lead to brittle tests. For example, we may care about `A` occurring
-before both `B` and `C`, but aren't interested in the relative order
-of `B` and `C`. In this case, the test should reflect our real intent,
-instead of being overly constraining.
+Sometimes requiring everything to occur in a predetermined order can lead to
+brittle tests. For example, we may care about `A` occurring before both `B` and
+`C`, but aren't interested in the relative order of `B` and `C`. In this case,
+the test should reflect our real intent, instead of being overly constraining.
-Google Mock allows you to impose an arbitrary DAG (directed acyclic
-graph) on the calls. One way to express the DAG is to use the
-[After](cheat_sheet.md#the-after-clause) clause of `EXPECT_CALL`.
+gMock allows you to impose an arbitrary DAG (directed acyclic graph) on the
+calls. One way to express the DAG is to use the [After](#AfterClause) clause of
+`EXPECT_CALL`.
-Another way is via the `InSequence()` clause (not the same as the
-`InSequence` class), which we borrowed from jMock 2. It's less
-flexible than `After()`, but more convenient when you have long chains
-of sequential calls, as it doesn't require you to come up with
-different names for the expectations in the chains. Here's how it
-works:
+Another way is via the `InSequence()` clause (not the same as the `InSequence`
+class), which we borrowed from jMock 2. It's less flexible than `After()`, but
+more convenient when you have long chains of sequential calls, as it doesn't
+require you to come up with different names for the expectations in the chains.
+Here's how it works:
-If we view `EXPECT_CALL()` statements as nodes in a graph, and add an
-edge from node A to node B wherever A must occur before B, we can get
-a DAG. We use the term "sequence" to mean a directed path in this
-DAG. Now, if we decompose the DAG into sequences, we just need to know
-which sequences each `EXPECT_CALL()` belongs to in order to be able to
-reconstruct the original DAG.
+If we view `EXPECT_CALL()` statements as nodes in a graph, and add an edge from
+node A to node B wherever A must occur before B, we can get a DAG. We use the
+term "sequence" to mean a directed path in this DAG. Now, if we decompose the
+DAG into sequences, we just need to know which sequences each `EXPECT_CALL()`
+belongs to in order to be able to reconstruct the original DAG.
-So, to specify the partial order on the expectations we need to do two
-things: first to define some `Sequence` objects, and then for each
-`EXPECT_CALL()` say which `Sequence` objects it is part
-of. Expectations in the same sequence must occur in the order they are
-written. For example,
+So, to specify the partial order on the expectations we need to do two things:
+first to define some `Sequence` objects, and then for each `EXPECT_CALL()` say
+which `Sequence` objects it is part of.
+
+Expectations in the same sequence must occur in the order they are written. For
+example,
```cpp
- using ::testing::Sequence;
-
+using ::testing::Sequence;
+...
Sequence s1, s2;
EXPECT_CALL(foo, A())
@@ -1428,110 +1745,109 @@
.InSequence(s2);
```
-specifies the following DAG (where `s1` is `A -> B`, and `s2` is `A ->
-C -> D`):
+specifies the following DAG (where `s1` is `A -> B`, and `s2` is `A -> C -> D`):
-```
+```text
+---> B
|
A ---|
|
- +---> C ---> D
+ +---> C ---> D
```
-This means that A must occur before B and C, and C must occur before
-D. There's no restriction about the order other than these.
+This means that A must occur before B and C, and C must occur before D. There's
+no restriction about the order other than these.
-## Controlling When an Expectation Retires ##
+#### Controlling When an Expectation Retires
-When a mock method is called, Google Mock only consider expectations
-that are still active. An expectation is active when created, and
-becomes inactive (aka _retires_) when a call that has to occur later
-has occurred. For example, in
+When a mock method is called, gMock only considers expectations that are still
+active. An expectation is active when created, and becomes inactive (aka
+*retires*) when a call that has to occur later has occurred. For example, in
```cpp
- using ::testing::_;
- using ::testing::Sequence;
-
+using ::testing::_;
+using ::testing::Sequence;
+...
Sequence s1, s2;
- EXPECT_CALL(log, Log(WARNING, _, "File too large.")) // #1
+ EXPECT_CALL(log, Log(WARNING, _, "File too large.")) // #1
.Times(AnyNumber())
.InSequence(s1, s2);
- EXPECT_CALL(log, Log(WARNING, _, "Data set is empty.")) // #2
+ EXPECT_CALL(log, Log(WARNING, _, "Data set is empty.")) // #2
.InSequence(s1);
- EXPECT_CALL(log, Log(WARNING, _, "User not found.")) // #3
+ EXPECT_CALL(log, Log(WARNING, _, "User not found.")) // #3
.InSequence(s2);
```
-as soon as either #2 or #3 is matched, #1 will retire. If a warning
-`"File too large."` is logged after this, it will be an error.
+as soon as either #2 or #3 is matched, #1 will retire. If a warning `"File too
+large."` is logged after this, it will be an error.
-Note that an expectation doesn't retire automatically when it's
-saturated. For example,
+Note that an expectation doesn't retire automatically when it's saturated. For
+example,
```cpp
using ::testing::_;
...
- EXPECT_CALL(log, Log(WARNING, _, _)); // #1
- EXPECT_CALL(log, Log(WARNING, _, "File too large.")); // #2
+ EXPECT_CALL(log, Log(WARNING, _, _)); // #1
+ EXPECT_CALL(log, Log(WARNING, _, "File too large.")); // #2
```
-says that there will be exactly one warning with the message `"File
-too large."`. If the second warning contains this message too, #2 will
-match again and result in an upper-bound-violated error.
+says that there will be exactly one warning with the message `"File too
+large."`. If the second warning contains this message too, #2 will match again
+and result in an upper-bound-violated error.
-If this is not what you want, you can ask an expectation to retire as
-soon as it becomes saturated:
+If this is not what you want, you can ask an expectation to retire as soon as it
+becomes saturated:
```cpp
using ::testing::_;
...
- EXPECT_CALL(log, Log(WARNING, _, _)); // #1
- EXPECT_CALL(log, Log(WARNING, _, "File too large.")) // #2
+ EXPECT_CALL(log, Log(WARNING, _, _)); // #1
+ EXPECT_CALL(log, Log(WARNING, _, "File too large.")) // #2
.RetiresOnSaturation();
```
-Here #2 can be used only once, so if you have two warnings with the
-message `"File too large."`, the first will match #2 and the second
-will match #1 - there will be no error.
+Here #2 can be used only once, so if you have two warnings with the message
+`"File too large."`, the first will match #2 and the second will match #1 -
+there will be no error.
-# Using Actions #
+### Using Actions
-## Returning References from Mock Methods ##
+#### Returning References from Mock Methods
-If a mock function's return type is a reference, you need to use
-`ReturnRef()` instead of `Return()` to return a result:
+If a mock function's return type is a reference, you need to use `ReturnRef()`
+instead of `Return()` to return a result:
```cpp
using ::testing::ReturnRef;
class MockFoo : public Foo {
public:
- MOCK_METHOD0(GetBar, Bar&());
+ MOCK_METHOD(Bar&, GetBar, (), (override));
};
...
-
MockFoo foo;
Bar bar;
EXPECT_CALL(foo, GetBar())
.WillOnce(ReturnRef(bar));
+...
```
-## Returning Live Values from Mock Methods ##
+#### Returning Live Values from Mock Methods
-The `Return(x)` action saves a copy of `x` when the action is
-_created_, and always returns the same value whenever it's
-executed. Sometimes you may want to instead return the _live_ value of
-`x` (i.e. its value at the time when the action is _executed_.).
+The `Return(x)` action saves a copy of `x` when the action is created, and
+always returns the same value whenever it's executed. Sometimes you may want to
+instead return the *live* value of `x` (i.e. its value at the time when the
+action is *executed*.). Use either `ReturnRef()` or `ReturnPointee()` for this
+purpose.
If the mock function's return type is a reference, you can do it using
-`ReturnRef(x)`, as shown in the previous recipe ("Returning References
-from Mock Methods"). However, Google Mock doesn't let you use
-`ReturnRef()` in a mock function whose return type is not a reference,
-as doing that usually indicates a user error. So, what shall you do?
+`ReturnRef(x)`, as shown in the previous recipe ("Returning References from Mock
+Methods"). However, gMock doesn't let you use `ReturnRef()` in a mock function
+whose return type is not a reference, as doing that usually indicates a user
+error. So, what shall you do?
-You may be tempted to try `ByRef()`:
+Though you may be tempted, DO NOT use `ByRef()`:
```cpp
using testing::ByRef;
@@ -1539,36 +1855,34 @@
class MockFoo : public Foo {
public:
- MOCK_METHOD0(GetValue, int());
+ MOCK_METHOD(int, GetValue, (), (override));
};
...
int x = 0;
MockFoo foo;
EXPECT_CALL(foo, GetValue())
- .WillRepeatedly(Return(ByRef(x)));
+ .WillRepeatedly(Return(ByRef(x))); // Wrong!
x = 42;
EXPECT_EQ(42, foo.GetValue());
```
Unfortunately, it doesn't work here. The above code will fail with error:
-```
+```text
Value of: foo.GetValue()
Actual: 0
Expected: 42
```
-The reason is that `Return(value)` converts `value` to the actual
-return type of the mock function at the time when the action is
-_created_, not when it is _executed_. (This behavior was chosen for
-the action to be safe when `value` is a proxy object that references
-some temporary objects.) As a result, `ByRef(x)` is converted to an
-`int` value (instead of a `const int&`) when the expectation is set,
-and `Return(ByRef(x))` will always return 0.
+The reason is that `Return(*value*)` converts `value` to the actual return type
+of the mock function at the time when the action is *created*, not when it is
+*executed*. (This behavior was chosen for the action to be safe when `value` is
+a proxy object that references some temporary objects.) As a result, `ByRef(x)`
+is converted to an `int` value (instead of a `const int&`) when the expectation
+is set, and `Return(ByRef(x))` will always return 0.
-`ReturnPointee(pointer)` was provided to solve this problem
-specifically. It returns the value pointed to by `pointer` at the time
-the action is _executed_:
+`ReturnPointee(pointer)` was provided to solve this problem specifically. It
+returns the value pointed to by `pointer` at the time the action is *executed*:
```cpp
using testing::ReturnPointee;
@@ -1581,21 +1895,21 @@
EXPECT_EQ(42, foo.GetValue()); // This will succeed now.
```
-## Combining Actions ##
+#### Combining Actions
-Want to do more than one thing when a function is called? That's
-fine. `DoAll()` allow you to do sequence of actions every time. Only
-the return value of the last action in the sequence will be used.
+Want to do more than one thing when a function is called? That's fine. `DoAll()`
+allow you to do sequence of actions every time. Only the return value of the
+last action in the sequence will be used.
```cpp
+using ::testing::_;
using ::testing::DoAll;
class MockFoo : public Foo {
public:
- MOCK_METHOD1(Bar, bool(int n));
+ MOCK_METHOD(bool, Bar, (int n), (override));
};
...
-
EXPECT_CALL(foo, Bar(_))
.WillOnce(DoAll(action_1,
action_2,
@@ -1603,42 +1917,65 @@
action_n));
```
-## Mocking Side Effects ##
+#### Verifying Complex Arguments {#SaveArgVerify}
-Sometimes a method exhibits its effect not via returning a value but
-via side effects. For example, it may change some global state or
-modify an output argument. To mock side effects, in general you can
-define your own action by implementing `::testing::ActionInterface`.
+If you want to verify that a method is called with a particular argument but the
+match criteria is complex, it can be difficult to distinguish between
+cardinality failures (calling the method the wrong number of times) and argument
+match failures. Similarly, if you are matching multiple parameters, it may not
+be easy to distinguishing which argument failed to match. For example:
+
+```cpp
+ // Not ideal: this could fail because of a problem with arg1 or arg2, or maybe
+ // just the method wasn't called.
+ EXPECT_CALL(foo, SendValues(_, ElementsAre(1, 4, 4, 7), EqualsProto( ... )));
+```
+
+You can instead save the arguments and test them individually:
+
+```cpp
+ EXPECT_CALL(foo, SendValues)
+ .WillOnce(DoAll(SaveArg<1>(&actual_array), SaveArg<2>(&actual_proto)));
+ ... run the test
+ EXPECT_THAT(actual_array, ElementsAre(1, 4, 4, 7));
+ EXPECT_THAT(actual_proto, EqualsProto( ... ));
+```
+
+#### Mocking Side Effects {#MockingSideEffects}
+
+Sometimes a method exhibits its effect not via returning a value but via side
+effects. For example, it may change some global state or modify an output
+argument. To mock side effects, in general you can define your own action by
+implementing `::testing::ActionInterface`.
If all you need to do is to change an output argument, the built-in
`SetArgPointee()` action is convenient:
```cpp
+using ::testing::_;
using ::testing::SetArgPointee;
class MockMutator : public Mutator {
public:
- MOCK_METHOD2(Mutate, void(bool mutate, int* value));
+ MOCK_METHOD(void, Mutate, (bool mutate, int* value), (override));
...
-};
+}
...
-
MockMutator mutator;
EXPECT_CALL(mutator, Mutate(true, _))
.WillOnce(SetArgPointee<1>(5));
```
-In this example, when `mutator.Mutate()` is called, we will assign 5
-to the `int` variable pointed to by argument #1
-(0-based).
+In this example, when `mutator.Mutate()` is called, we will assign 5 to the
+`int` variable pointed to by argument #1 (0-based).
-`SetArgPointee()` conveniently makes an internal copy of the
-value you pass to it, removing the need to keep the value in scope and
-alive. The implication however is that the value must have a copy
-constructor and assignment operator.
+`SetArgPointee()` conveniently makes an internal copy of the value you pass to
+it, removing the need to keep the value in scope and alive. The implication
+however is that the value must have a copy constructor and assignment operator.
If the mock method also needs to return a value as well, you can chain
-`SetArgPointee()` with `Return()` using `DoAll()`:
+`SetArgPointee()` with `Return()` using `DoAll()`, remembering to put the
+`Return()` statement last:
```cpp
using ::testing::_;
@@ -1648,20 +1985,22 @@
class MockMutator : public Mutator {
public:
...
- MOCK_METHOD1(MutateInt, bool(int* value));
-};
+ MOCK_METHOD(bool, MutateInt, (int* value), (override));
+}
...
-
MockMutator mutator;
EXPECT_CALL(mutator, MutateInt(_))
.WillOnce(DoAll(SetArgPointee<0>(5),
Return(true)));
```
-If the output argument is an array, use the
-`SetArrayArgument<N>(first, last)` action instead. It copies the
-elements in source range `[first, last)` to the array pointed to by
-the `N`-th (0-based) argument:
+Note, however, that if you use the `ReturnOKWith()` method, it will override the
+values provided by `SetArgPointee()` in the response parameters of your function
+call.
+
+If the output argument is an array, use the `SetArrayArgument<N>(first, last)`
+action instead. It copies the elements in source range `[first, last)` to the
+array pointed to by the `N`-th (0-based) argument:
```cpp
using ::testing::NotNull;
@@ -1669,13 +2008,12 @@
class MockArrayMutator : public ArrayMutator {
public:
- MOCK_METHOD2(Mutate, void(int* values, int num_values));
+ MOCK_METHOD(void, Mutate, (int* values, int num_values), (override));
...
-};
+}
...
-
MockArrayMutator mutator;
- int values[5] = { 1, 2, 3, 4, 5 };
+ int values[5] = {1, 2, 3, 4, 5};
EXPECT_CALL(mutator, Mutate(NotNull(), 5))
.WillOnce(SetArrayArgument<0>(values, values + 5));
```
@@ -1688,11 +2026,11 @@
class MockRolodex : public Rolodex {
public:
- MOCK_METHOD1(GetNames, void(std::back_insert_iterator<vector<string> >));
+ MOCK_METHOD(void, GetNames, (std::back_insert_iterator<vector<string>>),
+ (override));
...
-};
+}
...
-
MockRolodex rolodex;
vector<string> names;
names.push_back("George");
@@ -1702,9 +2040,11 @@
.WillOnce(SetArrayArgument<0>(names.begin(), names.end()));
```
-## Changing a Mock Object's Behavior Based on the State ##
+#### Changing a Mock Object's Behavior Based on the State
-If you expect a call to change the behavior of a mock object, you can use `::testing::InSequence` to specify different behaviors before and after the call:
+If you expect a call to change the behavior of a mock object, you can use
+`::testing::InSequence` to specify different behaviors before and after the
+call:
```cpp
using ::testing::InSequence;
@@ -1712,19 +2052,21 @@
...
{
- InSequence seq;
- EXPECT_CALL(my_mock, IsDirty())
- .WillRepeatedly(Return(true));
- EXPECT_CALL(my_mock, Flush());
- EXPECT_CALL(my_mock, IsDirty())
- .WillRepeatedly(Return(false));
+ InSequence seq;
+ EXPECT_CALL(my_mock, IsDirty())
+ .WillRepeatedly(Return(true));
+ EXPECT_CALL(my_mock, Flush());
+ EXPECT_CALL(my_mock, IsDirty())
+ .WillRepeatedly(Return(false));
}
my_mock.FlushIfDirty();
```
-This makes `my_mock.IsDirty()` return `true` before `my_mock.Flush()` is called and return `false` afterwards.
+This makes `my_mock.IsDirty()` return `true` before `my_mock.Flush()` is called
+and return `false` afterwards.
-If the behavior change is more complex, you can store the effects in a variable and make a mock method get its return value from that variable:
+If the behavior change is more complex, you can store the effects in a variable
+and make a mock method get its return value from that variable:
```cpp
using ::testing::_;
@@ -1734,35 +2076,38 @@
ACTION_P(ReturnPointee, p) { return *p; }
...
int previous_value = 0;
- EXPECT_CALL(my_mock, GetPrevValue())
+ EXPECT_CALL(my_mock, GetPrevValue)
.WillRepeatedly(ReturnPointee(&previous_value));
- EXPECT_CALL(my_mock, UpdateValue(_))
+ EXPECT_CALL(my_mock, UpdateValue)
.WillRepeatedly(SaveArg<0>(&previous_value));
my_mock.DoSomethingToUpdateValue();
```
-Here `my_mock.GetPrevValue()` will always return the argument of the last `UpdateValue()` call.
+Here `my_mock.GetPrevValue()` will always return the argument of the last
+`UpdateValue()` call.
-## Setting the Default Value for a Return Type ##
+#### Setting the Default Value for a Return Type {#DefaultValue}
-If a mock method's return type is a built-in C++ type or pointer, by
-default it will return 0 when invoked. Also, in C++ 11 and above, a mock
-method whose return type has a default constructor will return a default-constructed
-value by default. You only need to specify an
-action if this default value doesn't work for you.
+If a mock method's return type is a built-in C++ type or pointer, by default it
+will return 0 when invoked. Also, in C++ 11 and above, a mock method whose
+return type has a default constructor will return a default-constructed value by
+default. You only need to specify an action if this default value doesn't work
+for you.
-Sometimes, you may want to change this default value, or you may want
-to specify a default value for types Google Mock doesn't know
-about. You can do this using the `::testing::DefaultValue` class
-template:
+Sometimes, you may want to change this default value, or you may want to specify
+a default value for types gMock doesn't know about. You can do this using the
+`::testing::DefaultValue` class template:
```cpp
+using ::testing::DefaultValue;
+
class MockFoo : public Foo {
public:
- MOCK_METHOD0(CalculateBar, Bar());
+ MOCK_METHOD(Bar, CalculateBar, (), (override));
};
-...
+
+...
Bar default_bar;
// Sets the default return value for type Bar.
DefaultValue<Bar>::Set(default_bar);
@@ -1779,18 +2124,17 @@
DefaultValue<Bar>::Clear();
```
-Please note that changing the default value for a type can make you
-tests hard to understand. We recommend you to use this feature
-judiciously. For example, you may want to make sure the `Set()` and
-`Clear()` calls are right next to the code that uses your mock.
+Please note that changing the default value for a type can make you tests hard
+to understand. We recommend you to use this feature judiciously. For example,
+you may want to make sure the `Set()` and `Clear()` calls are right next to the
+code that uses your mock.
-## Setting the Default Actions for a Mock Method ##
+#### Setting the Default Actions for a Mock Method
-You've learned how to change the default value of a given
-type. However, this may be too coarse for your purpose: perhaps you
-have two mock methods with the same return type and you want them to
-have different behaviors. The `ON_CALL()` macro allows you to
-customize your mock's behavior at the method level:
+You've learned how to change the default value of a given type. However, this
+may be too coarse for your purpose: perhaps you have two mock methods with the
+same return type and you want them to have different behaviors. The `ON_CALL()`
+macro allows you to customize your mock's behavior at the method level:
```cpp
using ::testing::_;
@@ -1813,17 +2157,22 @@
foo.Sign(0); // This should return 0.
```
-As you may have guessed, when there are more than one `ON_CALL()`
-statements, the news order take precedence over the older ones. In
-other words, the **last** one that matches the function arguments will
-be used. This matching order allows you to set up the common behavior
-in a mock object's constructor or the test fixture's set-up phase and
-specialize the mock's behavior later.
+As you may have guessed, when there are more than one `ON_CALL()` statements,
+the newer ones in the order take precedence over the older ones. In other words,
+the **last** one that matches the function arguments will be used. This matching
+order allows you to set up the common behavior in a mock object's constructor or
+the test fixture's set-up phase and specialize the mock's behavior later.
-## Using Functions/Methods/Functors as Actions ##
+Note that both `ON_CALL` and `EXPECT_CALL` have the same "later statements take
+precedence" rule, but they don't interact. That is, `EXPECT_CALL`s have their
+own precedence order distinct from the `ON_CALL` precedence order.
-If the built-in actions don't suit you, you can easily use an existing
-function, method, or functor as an action:
+#### Using Functions/Methods/Functors/Lambdas/Callbacks as Actions {#FunctionsAsActions}
+
+If the built-in actions don't suit you, you can easily use an existing callable
+(function, `std::function`, method, functor, lambda, or `google3` permanent
+callback) as an action. Note that `Callback` or member function must be wrapped
+with `Invoke()`, whereas lambdas and functors will work by themselves.
```cpp
using ::testing::_;
@@ -1831,54 +2180,103 @@
class MockFoo : public Foo {
public:
- MOCK_METHOD2(Sum, int(int x, int y));
- MOCK_METHOD1(ComplexJob, bool(int x));
+ MOCK_METHOD(int, Sum, (int x, int y), (override));
+ MOCK_METHOD(bool, ComplexJob, (int x), (override));
};
int CalculateSum(int x, int y) { return x + y; }
+int Sum3(int x, int y, int z) { return x + y + z; }
class Helper {
public:
bool ComplexJob(int x);
};
-...
+...
MockFoo foo;
Helper helper;
EXPECT_CALL(foo, Sum(_, _))
- .WillOnce(Invoke(CalculateSum));
+ .WillOnce(&CalculateSum)
+ .WillRepeatedly(Invoke(NewPermanentCallback(Sum3, 1)));
EXPECT_CALL(foo, ComplexJob(_))
.WillOnce(Invoke(&helper, &Helper::ComplexJob));
+ .WillRepeatedly([](int x) { return x > 0; });
- foo.Sum(5, 6); // Invokes CalculateSum(5, 6).
- foo.ComplexJob(10); // Invokes helper.ComplexJob(10);
+ foo.Sum(5, 6); // Invokes CalculateSum(5, 6).
+ foo.Sum(2, 3); // Invokes Sum3(1, 2, 3).
+ foo.ComplexJob(10); // Invokes helper.ComplexJob(10).
+ foo.ComplexJob(-1); // Invokes the inline lambda.
```
-The only requirement is that the type of the function, etc must be
-_compatible_ with the signature of the mock function, meaning that the
-latter's arguments can be implicitly converted to the corresponding
-arguments of the former, and the former's return type can be
-implicitly converted to that of the latter. So, you can invoke
-something whose type is _not_ exactly the same as the mock function,
+The only requirement is that the type of the function, etc must be *compatible*
+with the signature of the mock function, meaning that the latter's arguments can
+be implicitly converted to the corresponding arguments of the former, and the
+former's return type can be implicitly converted to that of the latter. So, you
+can invoke something whose type is *not* exactly the same as the mock function,
as long as it's safe to do so - nice, huh?
-## Invoking a Function/Method/Functor Without Arguments ##
+**`Note:`{.escaped}**
-`Invoke()` is very useful for doing actions that are more complex. It
-passes the mock function's arguments to the function or functor being
-invoked such that the callee has the full context of the call to work
-with. If the invoked function is not interested in some or all of the
-arguments, it can simply ignore them.
+* The action takes ownership of the callback and will delete it when the
+ action itself is destructed.
+* If the type of a callback is derived from a base callback type `C`, you need
+ to implicitly cast it to `C` to resolve the overloading, e.g.
-Yet, a common pattern is that a test author wants to invoke a function
-without the arguments of the mock function. `Invoke()` allows her to
-do that using a wrapper function that throws away the arguments before
-invoking an underlining nullary function. Needless to say, this can be
-tedious and obscures the intent of the test.
+ ```cpp
+ using ::testing::Invoke;
+ ...
+ ResultCallback<bool>* is_ok = ...;
+ ... Invoke(is_ok) ...; // This works.
-`InvokeWithoutArgs()` solves this problem. It's like `Invoke()` except
-that it doesn't pass the mock function's arguments to the
-callee. Here's an example:
+ BlockingClosure* done = new BlockingClosure;
+ ... Invoke(implicit_cast<Closure*>(done)) ...; // The cast is necessary.
+ ```
+
+#### Using Functions with Extra Info as Actions
+
+The function or functor you call using `Invoke()` must have the same number of
+arguments as the mock function you use it for. Sometimes you may have a function
+that takes more arguments, and you are willing to pass in the extra arguments
+yourself to fill the gap. You can do this in gMock using callbacks with
+pre-bound arguments. Here's an example:
+
+```cpp
+using ::testing::Invoke;
+
+class MockFoo : public Foo {
+ public:
+ MOCK_METHOD(char, DoThis, (int n), (override));
+};
+
+char SignOfSum(int x, int y) {
+ const int sum = x + y;
+ return (sum > 0) ? '+' : (sum < 0) ? '-' : '0';
+}
+
+TEST_F(FooTest, Test) {
+ MockFoo foo;
+
+ EXPECT_CALL(foo, DoThis(2))
+ .WillOnce(Invoke(NewPermanentCallback(SignOfSum, 5)));
+ EXPECT_EQ('+', foo.DoThis(2)); // Invokes SignOfSum(5, 2).
+}
+```
+
+#### Invoking a Function/Method/Functor/Lambda/Callback Without Arguments
+
+`Invoke()` is very useful for doing actions that are more complex. It passes the
+mock function's arguments to the function, etc being invoked such that the
+callee has the full context of the call to work with. If the invoked function is
+not interested in some or all of the arguments, it can simply ignore them.
+
+Yet, a common pattern is that a test author wants to invoke a function without
+the arguments of the mock function. `Invoke()` allows her to do that using a
+wrapper function that throws away the arguments before invoking an underlining
+nullary function. Needless to say, this can be tedious and obscures the intent
+of the test.
+
+`InvokeWithoutArgs()` solves this problem. It's like `Invoke()` except that it
+doesn't pass the mock function's arguments to the callee. Here's an example:
```cpp
using ::testing::_;
@@ -1886,28 +2284,50 @@
class MockFoo : public Foo {
public:
- MOCK_METHOD1(ComplexJob, bool(int n));
+ MOCK_METHOD(bool, ComplexJob, (int n), (override));
};
bool Job1() { ... }
-...
+bool Job2(int n, char c) { ... }
+...
MockFoo foo;
EXPECT_CALL(foo, ComplexJob(_))
- .WillOnce(InvokeWithoutArgs(Job1));
+ .WillOnce(InvokeWithoutArgs(Job1))
+ .WillOnce(InvokeWithoutArgs(NewPermanentCallback(Job2, 5, 'a')));
foo.ComplexJob(10); // Invokes Job1().
+ foo.ComplexJob(20); // Invokes Job2(5, 'a').
```
-## Invoking an Argument of the Mock Function ##
+**`Note:`{.escaped}**
-Sometimes a mock function will receive a function pointer or a functor
-(in other words, a "callable") as an argument, e.g.
+* The action takes ownership of the callback and will delete it when the
+ action itself is destructed.
+* If the type of a callback is derived from a base callback type `C`, you need
+ to implicitly cast it to `C` to resolve the overloading, e.g.
+
+ ```cpp
+ using ::testing::InvokeWithoutArgs;
+ ...
+ ResultCallback<bool>* is_ok = ...;
+ ... InvokeWithoutArgs(is_ok) ...; // This works.
+
+ BlockingClosure* done = ...;
+ ... InvokeWithoutArgs(implicit_cast<Closure*>(done)) ...;
+ // The cast is necessary.
+ ```
+
+#### Invoking an Argument of the Mock Function
+
+Sometimes a mock function will receive a function pointer, a functor, or a
+`google3`-style callback (in other words, a "callable") as an argument, e.g.
```cpp
class MockFoo : public Foo {
public:
- MOCK_METHOD2(DoThis, bool(int n, bool (*fp)(int)));
+ MOCK_METHOD(bool, DoThis, (int n, (ResultCallback1<bool, int>* callback)),
+ (override));
};
```
@@ -1919,23 +2339,24 @@
MockFoo foo;
EXPECT_CALL(foo, DoThis(_, _))
.WillOnce(...);
- // Will execute (*fp)(5), where fp is the
- // second argument DoThis() receives.
+ // Will execute callback->Run(5), where callback is the
+ // second argument DoThis() receives.
```
-Arghh, you need to refer to a mock function argument but your version
-of C++ has no lambdas, so you have to define your own action. :-(
-Or do you really?
+NOTE: The section below is legacy documentation from before C++ had lambdas:
-Well, Google Mock has an action to solve _exactly_ this problem:
+Arghh, you need to refer to a mock function argument but C++ has no lambda
+(yet), so you have to define your own action. :-( Or do you really?
+
+Well, gMock has an action to solve *exactly* this problem:
```cpp
- InvokeArgument<N>(arg_1, arg_2, ..., arg_m)
+InvokeArgument<N>(arg_1, arg_2, ..., arg_m)
```
-will invoke the `N`-th (0-based) argument the mock function receives,
-with `arg_1`, `arg_2`, ..., and `arg_m`. No matter if the argument is
-a function pointer or a functor, Google Mock handles them both.
+will invoke the `N`-th (0-based) argument the mock function receives, with
+`arg_1`, `arg_2`, ..., and `arg_m`. No matter if the argument is a function
+pointer, a functor, or a callback. gMock handles them all.
With that, you could write:
@@ -1945,67 +2366,68 @@
...
EXPECT_CALL(foo, DoThis(_, _))
.WillOnce(InvokeArgument<1>(5));
- // Will execute (*fp)(5), where fp is the
- // second argument DoThis() receives.
+ // Will execute callback->Run(5), where callback is the
+ // second argument DoThis() receives.
```
-What if the callable takes an argument by reference? No problem - just
-wrap it inside `ByRef()`:
+What if the callable takes an argument by reference? No problem - just wrap it
+inside `ByRef()`:
```cpp
-...
- MOCK_METHOD1(Bar, bool(bool (*fp)(int, const Helper&)));
-...
-using ::testing::_;
-using ::testing::ByRef;
-using ::testing::InvokeArgument;
-...
-
+ ...
+ MOCK_METHOD(bool, Bar,
+ ((ResultCallback2<bool, int, const Helper&>* callback)),
+ (override));
+ ...
+ using ::testing::_;
+ using ::testing::ByRef;
+ using ::testing::InvokeArgument;
+ ...
MockFoo foo;
Helper helper;
...
EXPECT_CALL(foo, Bar(_))
.WillOnce(InvokeArgument<0>(5, ByRef(helper)));
- // ByRef(helper) guarantees that a reference to helper, not a copy of it,
- // will be passed to the callable.
+ // ByRef(helper) guarantees that a reference to helper, not a copy of it,
+ // will be passed to the callback.
```
-What if the callable takes an argument by reference and we do **not**
-wrap the argument in `ByRef()`? Then `InvokeArgument()` will _make a
-copy_ of the argument, and pass a _reference to the copy_, instead of
-a reference to the original value, to the callable. This is especially
-handy when the argument is a temporary value:
+What if the callable takes an argument by reference and we do **not** wrap the
+argument in `ByRef()`? Then `InvokeArgument()` will *make a copy* of the
+argument, and pass a *reference to the copy*, instead of a reference to the
+original value, to the callable. This is especially handy when the argument is a
+temporary value:
```cpp
-...
- MOCK_METHOD1(DoThat, bool(bool (*f)(const double& x, const string& s)));
-...
-using ::testing::_;
-using ::testing::InvokeArgument;
-...
-
+ ...
+ MOCK_METHOD(bool, DoThat, (bool (*f)(const double& x, const string& s)),
+ (override));
+ ...
+ using ::testing::_;
+ using ::testing::InvokeArgument;
+ ...
MockFoo foo;
...
EXPECT_CALL(foo, DoThat(_))
.WillOnce(InvokeArgument<0>(5.0, string("Hi")));
- // Will execute (*f)(5.0, string("Hi")), where f is the function pointer
- // DoThat() receives. Note that the values 5.0 and string("Hi") are
- // temporary and dead once the EXPECT_CALL() statement finishes. Yet
- // it's fine to perform this action later, since a copy of the values
- // are kept inside the InvokeArgument action.
+ // Will execute (*f)(5.0, string("Hi")), where f is the function pointer
+ // DoThat() receives. Note that the values 5.0 and string("Hi") are
+ // temporary and dead once the EXPECT_CALL() statement finishes. Yet
+ // it's fine to perform this action later, since a copy of the values
+ // are kept inside the InvokeArgument action.
```
-## Ignoring an Action's Result ##
+#### Ignoring an Action's Result
-Sometimes you have an action that returns _something_, but you need an
-action that returns `void` (perhaps you want to use it in a mock
-function that returns `void`, or perhaps it needs to be used in
-`DoAll()` and it's not the last in the list). `IgnoreResult()` lets
-you do that. For example:
+Sometimes you have an action that returns *something*, but you need an action
+that returns `void` (perhaps you want to use it in a mock function that returns
+`void`, or perhaps it needs to be used in `DoAll()` and it's not the last in the
+list). `IgnoreResult()` lets you do that. For example:
```cpp
using ::testing::_;
-using ::testing::Invoke;
+using ::testing::DoAll;
+using ::testing::IgnoreResult;
using ::testing::Return;
int Process(const MyData& data);
@@ -2013,127 +2435,129 @@
class MockFoo : public Foo {
public:
- MOCK_METHOD1(Abc, void(const MyData& data));
- MOCK_METHOD0(Xyz, bool());
+ MOCK_METHOD(void, Abc, (const MyData& data), (override));
+ MOCK_METHOD(bool, Xyz, (), (override));
};
-...
+ ...
MockFoo foo;
EXPECT_CALL(foo, Abc(_))
- // .WillOnce(Invoke(Process));
- // The above line won't compile as Process() returns int but Abc() needs
- // to return void.
- .WillOnce(IgnoreResult(Invoke(Process)));
-
+ // .WillOnce(Invoke(Process));
+ // The above line won't compile as Process() returns int but Abc() needs
+ // to return void.
+ .WillOnce(IgnoreResult(Process));
EXPECT_CALL(foo, Xyz())
- .WillOnce(DoAll(IgnoreResult(Invoke(DoSomething)),
- // Ignores the string DoSomething() returns.
+ .WillOnce(DoAll(IgnoreResult(DoSomething),
+ // Ignores the string DoSomething() returns.
Return(true)));
```
-Note that you **cannot** use `IgnoreResult()` on an action that already
-returns `void`. Doing so will lead to ugly compiler errors.
+Note that you **cannot** use `IgnoreResult()` on an action that already returns
+`void`. Doing so will lead to ugly compiler errors.
-## Selecting an Action's Arguments ##
+#### Selecting an Action's Arguments {#SelectingArgs}
-Say you have a mock function `Foo()` that takes seven arguments, and
-you have a custom action that you want to invoke when `Foo()` is
-called. Trouble is, the custom action only wants three arguments:
+Say you have a mock function `Foo()` that takes seven arguments, and you have a
+custom action that you want to invoke when `Foo()` is called. Trouble is, the
+custom action only wants three arguments:
```cpp
using ::testing::_;
using ::testing::Invoke;
...
- MOCK_METHOD7(Foo, bool(bool visible, const string& name, int x, int y,
- const map<pair<int, int>, double>& weight,
- double min_weight, double max_wight));
+ MOCK_METHOD(bool, Foo,
+ (bool visible, const string& name, int x, int y,
+ (const map<pair<int, int>>), double& weight, double min_weight,
+ double max_wight));
...
-
bool IsVisibleInQuadrant1(bool visible, int x, int y) {
return visible && x >= 0 && y >= 0;
}
...
-
- EXPECT_CALL(mock, Foo(_, _, _, _, _, _, _))
+ EXPECT_CALL(mock, Foo)
.WillOnce(Invoke(IsVisibleInQuadrant1)); // Uh, won't compile. :-(
```
-To please the compiler God, you can to define an "adaptor" that has
-the same signature as `Foo()` and calls the custom action with the
-right arguments:
+To please the compiler God, you need to define an "adaptor" that has the same
+signature as `Foo()` and calls the custom action with the right arguments:
```cpp
using ::testing::_;
using ::testing::Invoke;
-
+...
bool MyIsVisibleInQuadrant1(bool visible, const string& name, int x, int y,
const map<pair<int, int>, double>& weight,
double min_weight, double max_wight) {
return IsVisibleInQuadrant1(visible, x, y);
}
...
-
- EXPECT_CALL(mock, Foo(_, _, _, _, _, _, _))
+ EXPECT_CALL(mock, Foo)
.WillOnce(Invoke(MyIsVisibleInQuadrant1)); // Now it works.
```
But isn't this awkward?
-Google Mock provides a generic _action adaptor_, so you can spend your
-time minding more important business than writing your own
-adaptors. Here's the syntax:
+gMock provides a generic *action adaptor*, so you can spend your time minding
+more important business than writing your own adaptors. Here's the syntax:
```cpp
- WithArgs<N1, N2, ..., Nk>(action)
+WithArgs<N1, N2, ..., Nk>(action)
```
-creates an action that passes the arguments of the mock function at
-the given indices (0-based) to the inner `action` and performs
-it. Using `WithArgs`, our original example can be written as:
+creates an action that passes the arguments of the mock function at the given
+indices (0-based) to the inner `action` and performs it. Using `WithArgs`, our
+original example can be written as:
```cpp
using ::testing::_;
using ::testing::Invoke;
using ::testing::WithArgs;
...
- EXPECT_CALL(mock, Foo(_, _, _, _, _, _, _))
- .WillOnce(WithArgs<0, 2, 3>(Invoke(IsVisibleInQuadrant1)));
- // No need to define your own adaptor.
+ EXPECT_CALL(mock, Foo)
+ .WillOnce(WithArgs<0, 2, 3>(Invoke(IsVisibleInQuadrant1))); // No need to define your own adaptor.
```
-For better readability, Google Mock also gives you:
+For better readability, gMock also gives you:
- * `WithoutArgs(action)` when the inner `action` takes _no_ argument, and
- * `WithArg<N>(action)` (no `s` after `Arg`) when the inner `action` takes _one_ argument.
+* `WithoutArgs(action)` when the inner `action` takes *no* argument, and
+* `WithArg<N>(action)` (no `s` after `Arg`) when the inner `action` takes
+ *one* argument.
-As you may have realized, `InvokeWithoutArgs(...)` is just syntactic
-sugar for `WithoutArgs(Invoke(...))`.
+As you may have realized, `InvokeWithoutArgs(...)` is just syntactic sugar for
+`WithoutArgs(Invoke(...))`.
Here are more tips:
- * The inner action used in `WithArgs` and friends does not have to be `Invoke()` -- it can be anything.
- * You can repeat an argument in the argument list if necessary, e.g. `WithArgs<2, 3, 3, 5>(...)`.
- * You can change the order of the arguments, e.g. `WithArgs<3, 2, 1>(...)`.
- * The types of the selected arguments do _not_ have to match the signature of the inner action exactly. It works as long as they can be implicitly converted to the corresponding arguments of the inner action. For example, if the 4-th argument of the mock function is an `int` and `my_action` takes a `double`, `WithArg<4>(my_action)` will work.
+* The inner action used in `WithArgs` and friends does not have to be
+ `Invoke()` -- it can be anything.
+* You can repeat an argument in the argument list if necessary, e.g.
+ `WithArgs<2, 3, 3, 5>(...)`.
+* You can change the order of the arguments, e.g. `WithArgs<3, 2, 1>(...)`.
+* The types of the selected arguments do *not* have to match the signature of
+ the inner action exactly. It works as long as they can be implicitly
+ converted to the corresponding arguments of the inner action. For example,
+ if the 4-th argument of the mock function is an `int` and `my_action` takes
+ a `double`, `WithArg<4>(my_action)` will work.
-## Ignoring Arguments in Action Functions ##
+#### Ignoring Arguments in Action Functions
-The selecting-an-action's-arguments recipe showed us one way to make a
-mock function and an action with incompatible argument lists fit
-together. The downside is that wrapping the action in
-`WithArgs<...>()` can get tedious for people writing the tests.
+The [selecting-an-action's-arguments](#SelectingArgs) recipe showed us one way
+to make a mock function and an action with incompatible argument lists fit
+together. The downside is that wrapping the action in `WithArgs<...>()` can get
+tedious for people writing the tests.
-If you are defining a function, method, or functor to be used with
-`Invoke*()`, and you are not interested in some of its arguments, an
-alternative to `WithArgs` is to declare the uninteresting arguments as
-`Unused`. This makes the definition less cluttered and less fragile in
-case the types of the uninteresting arguments change. It could also
-increase the chance the action function can be reused. For example,
-given
+If you are defining a function (or method, functor, lambda, callback) to be used
+with `Invoke*()`, and you are not interested in some of its arguments, an
+alternative to `WithArgs` is to declare the uninteresting arguments as `Unused`.
+This makes the definition less cluttered and less fragile in case the types of
+the uninteresting arguments change. It could also increase the chance the action
+function can be reused. For example, given
```cpp
- MOCK_METHOD3(Foo, double(const string& label, double x, double y));
- MOCK_METHOD3(Bar, double(int index, double x, double y));
+ public:
+ MOCK_METHOD(double, Foo, double(const string& label, double x, double y),
+ (override));
+ MOCK_METHOD(double, Bar, (int index, double x, double y), (override));
```
instead of
@@ -2145,15 +2569,13 @@
double DistanceToOriginWithLabel(const string& label, double x, double y) {
return sqrt(x*x + y*y);
}
-
double DistanceToOriginWithIndex(int index, double x, double y) {
return sqrt(x*x + y*y);
}
...
-
- EXEPCT_CALL(mock, Foo("abc", _, _))
+ EXPECT_CALL(mock, Foo("abc", _, _))
.WillOnce(Invoke(DistanceToOriginWithLabel));
- EXEPCT_CALL(mock, Bar(5, _, _))
+ EXPECT_CALL(mock, Bar(5, _, _))
.WillOnce(Invoke(DistanceToOriginWithIndex));
```
@@ -2168,39 +2590,41 @@
return sqrt(x*x + y*y);
}
...
-
- EXEPCT_CALL(mock, Foo("abc", _, _))
+ EXPECT_CALL(mock, Foo("abc", _, _))
.WillOnce(Invoke(DistanceToOrigin));
- EXEPCT_CALL(mock, Bar(5, _, _))
+ EXPECT_CALL(mock, Bar(5, _, _))
.WillOnce(Invoke(DistanceToOrigin));
```
-## Sharing Actions ##
+#### Sharing Actions
-Just like matchers, a Google Mock action object consists of a pointer
-to a ref-counted implementation object. Therefore copying actions is
-also allowed and very efficient. When the last action that references
-the implementation object dies, the implementation object will be
-deleted.
+Just like matchers, a gMock action object consists of a pointer to a ref-counted
+implementation object. Therefore copying actions is also allowed and very
+efficient. When the last action that references the implementation object dies,
+the implementation object will be deleted.
-If you have some complex action that you want to use again and again,
-you may not have to build it from scratch every time. If the action
-doesn't have an internal state (i.e. if it always does the same thing
-no matter how many times it has been called), you can assign it to an
-action variable and use that variable repeatedly. For example:
+If you have some complex action that you want to use again and again, you may
+not have to build it from scratch everytime. If the action doesn't have an
+internal state (i.e. if it always does the same thing no matter how many times
+it has been called), you can assign it to an action variable and use that
+variable repeatedly. For example:
```cpp
+using ::testing::Action;
+using ::testing::DoAll;
+using ::testing::Return;
+using ::testing::SetArgPointee;
+...
Action<bool(int*)> set_flag = DoAll(SetArgPointee<0>(5),
Return(true));
... use set_flag in .WillOnce() and .WillRepeatedly() ...
```
-However, if the action has its own state, you may be surprised if you
-share the action object. Suppose you have an action factory
-`IncrementCounter(init)` which creates an action that increments and
-returns a counter whose initial value is `init`, using two actions
-created from the same expression and using a shared action will
-exihibit different behaviors. Example:
+However, if the action has its own state, you may be surprised if you share the
+action object. Suppose you have an action factory `IncrementCounter(init)` which
+creates an action that increments and returns a counter whose initial value is
+`init`, using two actions created from the same expression and using a shared
+action will exihibit different behaviors. Example:
```cpp
EXPECT_CALL(foo, DoThis())
@@ -2216,8 +2640,9 @@
versus
```cpp
+using ::testing::Action;
+...
Action<int()> increment = IncrementCounter(0);
-
EXPECT_CALL(foo, DoThis())
.WillRepeatedly(increment);
EXPECT_CALL(foo, DoThat())
@@ -2227,19 +2652,68 @@
foo.DoThat(); // Returns 3 - the counter is shared.
```
-# Misc Recipes on Using Google Mock #
+#### Testing Asynchronous Behavior
-## Mocking Methods That Use Move-Only Types ##
+One oft-encountered problem with gMock is that it can be hard to test
+asynchronous behavior. Suppose you had a `EventQueue` class that you wanted to
+test, and you created a separate `EventDispatcher` interface so that you could
+easily mock it out. However, the implementation of the class fired all the
+events on a background thread, which made test timings difficult. You could just
+insert `sleep()` statements and hope for the best, but that makes your test
+behavior nondeterministic. A better way is to use gMock actions and
+`Notification` objects to force your asynchronous test to behave synchronously.
+
+```cpp
+using ::testing::DoAll;
+using ::testing::InvokeWithoutArgs;
+using ::testing::Return;
+
+class MockEventDispatcher : public EventDispatcher {
+ MOCK_METHOD(bool, DispatchEvent, (int32), (override));
+};
+
+ACTION_P(Notify, notification) {
+ notification->Notify();
+}
+
+TEST(EventQueueTest, EnqueueEventTest) {
+ MockEventDispatcher mock_event_dispatcher;
+ EventQueue event_queue(&mock_event_dispatcher);
+
+ const int32 kEventId = 321;
+ Notification done;
+ EXPECT_CALL(mock_event_dispatcher, DispatchEvent(kEventId))
+ .WillOnce(Notify(&done));
+
+ event_queue.EnqueueEvent(kEventId);
+ done.WaitForNotification();
+}
+```
+
+In the example above, we set our normal gMock expectations, but then add an
+additional action to notify the `Notification` object. Now we can just call
+`Notification::WaitForNotification()` in the main thread to wait for the
+asynchronous call to finish. After that, our test suite is complete and we can
+safely exit.
+
+Note: this example has a downside: namely, if the expectation is not satisfied,
+our test will run forever. It will eventually time-out and fail, but it will
+take longer and be slightly harder to debug. To alleviate this problem, you can
+use `WaitForNotificationWithTimeout(ms)` instead of `WaitForNotification()`.
+
+### Misc Recipes on Using gMock
+
+#### Mocking Methods That Use Move-Only Types
C++11 introduced *move-only types*. A move-only-typed value can be moved from
-one object to another, but cannot be copied. `std::unique_ptr<T>` is
-probably the most commonly used move-only type.
+one object to another, but cannot be copied. `std::unique_ptr<T>` is probably
+the most commonly used move-only type.
Mocking a method that takes and/or returns move-only types presents some
challenges, but nothing insurmountable. This recipe shows you how you can do it.
Note that the support for move-only method arguments was only introduced to
gMock in April 2017; in older code, you may find more complex
-[workarounds](#legacy-workarounds-for-move-only-types) for lack of this feature.
+[workarounds](#LegacyMoveOnly) for lack of this feature.
Let’s say we are working on a fictional project that lets one post and share
snippets called “buzzes”. Your code uses these types:
@@ -2264,8 +2738,8 @@
A `Buzz` object represents a snippet being posted. A class that implements the
`Buzzer` interface is capable of creating and sharing `Buzz`es. Methods in
-`Buzzer` may return a `unique_ptr<Buzz>` or take a
-`unique_ptr<Buzz>`. Now we need to mock `Buzzer` in our tests.
+`Buzzer` may return a `unique_ptr<Buzz>` or take a `unique_ptr<Buzz>`. Now we
+need to mock `Buzzer` in our tests.
To mock a method that accepts or returns move-only types, you just use the
familiar `MOCK_METHOD` syntax as usual:
@@ -2273,8 +2747,9 @@
```cpp
class MockBuzzer : public Buzzer {
public:
- MOCK_METHOD1(MakeBuzz, std::unique_ptr<Buzz>(StringPiece text));
- MOCK_METHOD2(ShareBuzz, bool(std::unique_ptr<Buzz> buzz, int64_t timestamp));
+ MOCK_METHOD(std::unique_ptr<Buzz>, MakeBuzz, (StringPiece text), (override));
+ MOCK_METHOD(bool, ShareBuzz, (std::unique_ptr<Buzz> buzz, int64_t timestamp),
+ (override));
};
```
@@ -2290,9 +2765,9 @@
returns a `unique_ptr<Buzz>`.
As usual, if you set an expectation without an action (i.e. the `.WillOnce()` or
-`.WillRepeated()` clause), when that expectation fires, the default action for
-that method will be taken. Since `unique_ptr<>` has a default constructor
-that returns a null `unique_ptr`, that’s what you’ll get if you don’t specify an
+`.WillRepeatedly()` clause), when that expectation fires, the default action for
+that method will be taken. Since `unique_ptr<>` has a default constructor that
+returns a null `unique_ptr`, that’s what you’ll get if you don’t specify an
action:
```cpp
@@ -2304,7 +2779,7 @@
```
If you are not happy with the default action, you can tweak it as usual; see
-[Setting Default Actions](#setting-the-default-actions-for-a-mock-method).
+[Setting Default Actions](#OnCall).
If you just need to return a pre-defined move-only value, you can use the
`Return(ByMove(...))` action:
@@ -2321,9 +2796,9 @@
Note that `ByMove()` is essential here - if you drop it, the code won’t compile.
Quiz time! What do you think will happen if a `Return(ByMove(...))` action is
-performed more than once (e.g. you write
-`.WillRepeatedly(Return(ByMove(...)));`)? Come think of it, after the first
-time the action runs, the source value will be consumed (since it’s a move-only
+performed more than once (e.g. you write `...
+.WillRepeatedly(Return(ByMove(...)));`)? Come think of it, after the first time
+the action runs, the source value will be consumed (since it’s a move-only
value), so the next time around, there’s no value to move from -- you’ll get a
run-time error that `Return(ByMove(...))` can only be run once.
@@ -2341,22 +2816,22 @@
EXPECT_NE(nullptr, mock_buzzer_.MakeBuzz("x"));
```
-Every time this `EXPECT_CALL` fires, a new `unique_ptr<Buzz>` will be
-created and returned. You cannot do this with `Return(ByMove(...))`.
+Every time this `EXPECT_CALL` fires, a new `unique_ptr<Buzz>` will be created
+and returned. You cannot do this with `Return(ByMove(...))`.
That covers returning move-only values; but how do we work with methods
accepting move-only arguments? The answer is that they work normally, although
some actions will not compile when any of method's arguments are move-only. You
-can always use `Return`, or a [lambda or functor](#using-functionsmethodsfunctors-as-actions):
+can always use `Return`, or a [lambda or functor](#FunctionsAsActions):
```cpp
using ::testing::Unused;
- EXPECT_CALL(mock_buzzer_, ShareBuzz(NotNull(), _)) .WillOnce(Return(true));
+ EXPECT_CALL(mock_buzzer_, ShareBuzz(NotNull(), _)).WillOnce(Return(true));
EXPECT_TRUE(mock_buzzer_.ShareBuzz(MakeUnique<Buzz>(AccessLevel::kInternal)),
0);
- EXPECT_CALL(mock_buzzer_, ShareBuzz(_, _)) .WillOnce(
+ EXPECT_CALL(mock_buzzer_, ShareBuzz(_, _)).WillOnce(
[](std::unique_ptr<Buzz> buzz, Unused) { return buzz != nullptr; });
EXPECT_FALSE(mock_buzzer_.ShareBuzz(nullptr, 0));
```
@@ -2368,7 +2843,7 @@
A few actions (e.g. `DoAll`) copy their arguments internally, so they can never
work with non-copyable objects; you'll have to use functors instead.
-##### Legacy workarounds for move-only types
+##### Legacy workarounds for move-only types {#LegacyMoveOnly}
Support for move-only function arguments was only introduced to gMock in April
2017. In older code, you may encounter the following workaround for the lack of
@@ -2378,7 +2853,7 @@
```cpp
class MockBuzzer : public Buzzer {
public:
- MOCK_METHOD2(DoShareBuzz, bool(Buzz* buzz, Time timestamp));
+ MOCK_METHOD(bool, DoShareBuzz, (Buzz* buzz, Time timestamp));
bool ShareBuzz(std::unique_ptr<Buzz> buzz, Time timestamp) override {
return DoShareBuzz(buzz.get(), timestamp);
}
@@ -2400,27 +2875,24 @@
mock_buzzer_.ShareBuzz(MakeUnique<Buzz>(AccessLevel::kInternal), 0);
```
+#### Making the Compilation Faster
+Believe it or not, the *vast majority* of the time spent on compiling a mock
+class is in generating its constructor and destructor, as they perform
+non-trivial tasks (e.g. verification of the expectations). What's more, mock
+methods with different signatures have different types and thus their
+constructors/destructors need to be generated by the compiler separately. As a
+result, if you mock many different types of methods, compiling your mock class
+can get really slow.
-## Making the Compilation Faster ##
+If you are experiencing slow compilation, you can move the definition of your
+mock class' constructor and destructor out of the class body and into a `.cc`
+file. This way, even if you `#include` your mock class in N files, the compiler
+only needs to generate its constructor and destructor once, resulting in a much
+faster compilation.
-Believe it or not, the _vast majority_ of the time spent on compiling
-a mock class is in generating its constructor and destructor, as they
-perform non-trivial tasks (e.g. verification of the
-expectations). What's more, mock methods with different signatures
-have different types and thus their constructors/destructors need to
-be generated by the compiler separately. As a result, if you mock many
-different types of methods, compiling your mock class can get really
-slow.
-
-If you are experiencing slow compilation, you can move the definition
-of your mock class' constructor and destructor out of the class body
-and into a `.cpp` file. This way, even if you `#include` your mock
-class in N files, the compiler only needs to generate its constructor
-and destructor once, resulting in a much faster compilation.
-
-Let's illustrate the idea using an example. Here's the definition of a
-mock class before applying this recipe:
+Let's illustrate the idea using an example. Here's the definition of a mock
+class before applying this recipe:
```cpp
// File mock_foo.h.
@@ -2431,8 +2903,8 @@
// the compiler will generate them in every translation unit
// where this mock class is used.
- MOCK_METHOD0(DoThis, int());
- MOCK_METHOD1(DoThat, bool(const char* str));
+ MOCK_METHOD(int, DoThis, (), (override));
+ MOCK_METHOD(bool, DoThat, (const char* str), (override));
... more mock methods ...
};
```
@@ -2448,14 +2920,16 @@
MockFoo();
virtual ~MockFoo();
- MOCK_METHOD0(DoThis, int());
- MOCK_METHOD1(DoThat, bool(const char* str));
+ MOCK_METHOD(int, DoThis, (), (override));
+ MOCK_METHOD(bool, DoThat, (const char* str), (override));
... more mock methods ...
};
```
+
and
+
```cpp
-// File mock_foo.cpp.
+// File mock_foo.cc.
#include "path/to/mock_foo.h"
// The definitions may appear trivial, but the functions actually do a
@@ -2465,26 +2939,23 @@
MockFoo::~MockFoo() {}
```
-## Forcing a Verification ##
+#### Forcing a Verification
-When it's being destroyed, your friendly mock object will automatically
-verify that all expectations on it have been satisfied, and will
-generate [Google Test](../../googletest/) failures
-if not. This is convenient as it leaves you with one less thing to
-worry about. That is, unless you are not sure if your mock object will
-be destroyed.
+When it's being destroyed, your friendly mock object will automatically verify
+that all expectations on it have been satisfied, and will generate googletest
+failures if not. This is convenient as it leaves you with one less thing to
+worry about. That is, unless you are not sure if your mock object will be
+destroyed.
-How could it be that your mock object won't eventually be destroyed?
-Well, it might be created on the heap and owned by the code you are
-testing. Suppose there's a bug in that code and it doesn't delete the
-mock object properly - you could end up with a passing test when
-there's actually a bug.
+How could it be that your mock object won't eventually be destroyed? Well, it
+might be created on the heap and owned by the code you are testing. Suppose
+there's a bug in that code and it doesn't delete the mock object properly - you
+could end up with a passing test when there's actually a bug.
-Using a heap checker is a good idea and can alleviate the concern, but
-its implementation may not be 100% reliable. So, sometimes you do want
-to _force_ Google Mock to verify a mock object before it is
-(hopefully) destructed. You can do this with
-`Mock::VerifyAndClearExpectations(&mock_object)`:
+Using a heap checker is a good idea and can alleviate the concern, but its
+implementation is not 100% reliable. So, sometimes you do want to *force* gMock
+to verify a mock object before it is (hopefully) destructed. You can do this
+with `Mock::VerifyAndClearExpectations(&mock_object)`:
```cpp
TEST(MyServerTest, ProcessesRequest) {
@@ -2504,49 +2975,45 @@
} // server is destroyed when it goes out of scope here.
```
-**Tip:** The `Mock::VerifyAndClearExpectations()` function returns a
-`bool` to indicate whether the verification was successful (`true` for
-yes), so you can wrap that function call inside a `ASSERT_TRUE()` if
-there is no point going further when the verification has failed.
+**Tip:** The `Mock::VerifyAndClearExpectations()` function returns a `bool` to
+indicate whether the verification was successful (`true` for yes), so you can
+wrap that function call inside a `ASSERT_TRUE()` if there is no point going
+further when the verification has failed.
-## Using Check Points ##
+#### Using Check Points {#UsingCheckPoints}
-Sometimes you may want to "reset" a mock object at various check
-points in your test: at each check point, you verify that all existing
-expectations on the mock object have been satisfied, and then you set
-some new expectations on it as if it's newly created. This allows you
-to work with a mock object in "phases" whose sizes are each
-manageable.
+Sometimes you may want to "reset" a mock object at various check points in your
+test: at each check point, you verify that all existing expectations on the mock
+object have been satisfied, and then you set some new expectations on it as if
+it's newly created. This allows you to work with a mock object in "phases" whose
+sizes are each manageable.
-One such scenario is that in your test's `SetUp()` function, you may
-want to put the object you are testing into a certain state, with the
-help from a mock object. Once in the desired state, you want to clear
-all expectations on the mock, such that in the `TEST_F` body you can
-set fresh expectations on it.
+One such scenario is that in your test's `SetUp()` function, you may want to put
+the object you are testing into a certain state, with the help from a mock
+object. Once in the desired state, you want to clear all expectations on the
+mock, such that in the `TEST_F` body you can set fresh expectations on it.
-As you may have figured out, the `Mock::VerifyAndClearExpectations()`
-function we saw in the previous recipe can help you here. Or, if you
-are using `ON_CALL()` to set default actions on the mock object and
-want to clear the default actions as well, use
-`Mock::VerifyAndClear(&mock_object)` instead. This function does what
-`Mock::VerifyAndClearExpectations(&mock_object)` does and returns the
-same `bool`, **plus** it clears the `ON_CALL()` statements on
+As you may have figured out, the `Mock::VerifyAndClearExpectations()` function
+we saw in the previous recipe can help you here. Or, if you are using
+`ON_CALL()` to set default actions on the mock object and want to clear the
+default actions as well, use `Mock::VerifyAndClear(&mock_object)` instead. This
+function does what `Mock::VerifyAndClearExpectations(&mock_object)` does and
+returns the same `bool`, **plus** it clears the `ON_CALL()` statements on
`mock_object` too.
-Another trick you can use to achieve the same effect is to put the
-expectations in sequences and insert calls to a dummy "check-point"
-function at specific places. Then you can verify that the mock
-function calls do happen at the right time. For example, if you are
-exercising code:
+Another trick you can use to achieve the same effect is to put the expectations
+in sequences and insert calls to a dummy "check-point" function at specific
+places. Then you can verify that the mock function calls do happen at the right
+time. For example, if you are exercising code:
```cpp
-Foo(1);
-Foo(2);
-Foo(3);
+ Foo(1);
+ Foo(2);
+ Foo(3);
```
-and want to verify that `Foo(1)` and `Foo(3)` both invoke
-`mock.Bar("a")`, but `Foo(2)` doesn't invoke anything. You can write:
+and want to verify that `Foo(1)` and `Foo(3)` both invoke `mock.Bar("a")`, but
+`Foo(2)` doesn't invoke anything. You can write:
```cpp
using ::testing::MockFunction;
@@ -2572,44 +3039,42 @@
}
```
-The expectation spec says that the first `Bar("a")` must happen before
-check point "1", the second `Bar("a")` must happen after check point "2",
-and nothing should happen between the two check points. The explicit
-check points make it easy to tell which `Bar("a")` is called by which
-call to `Foo()`.
+The expectation spec says that the first `Bar("a")` must happen before check
+point "1", the second `Bar("a")` must happen after check point "2", and nothing
+should happen between the two check points. The explicit check points make it
+easy to tell which `Bar("a")` is called by which call to `Foo()`.
-## Mocking Destructors ##
+#### Mocking Destructors
-Sometimes you want to make sure a mock object is destructed at the
-right time, e.g. after `bar->A()` is called but before `bar->B()` is
-called. We already know that you can specify constraints on the order
-of mock function calls, so all we need to do is to mock the destructor
-of the mock function.
+Sometimes you want to make sure a mock object is destructed at the right time,
+e.g. after `bar->A()` is called but before `bar->B()` is called. We already know
+that you can specify constraints on the [order](#OrderedCalls) of mock function
+calls, so all we need to do is to mock the destructor of the mock function.
-This sounds simple, except for one problem: a destructor is a special
-function with special syntax and special semantics, and the
-`MOCK_METHOD0` macro doesn't work for it:
+This sounds simple, except for one problem: a destructor is a special function
+with special syntax and special semantics, and the `MOCK_METHOD` macro doesn't
+work for it:
```cpp
- MOCK_METHOD0(~MockFoo, void()); // Won't compile!
+MOCK_METHOD(void, ~MockFoo, ()); // Won't compile!
```
-The good news is that you can use a simple pattern to achieve the same
-effect. First, add a mock function `Die()` to your mock class and call
-it in the destructor, like this:
+The good news is that you can use a simple pattern to achieve the same effect.
+First, add a mock function `Die()` to your mock class and call it in the
+destructor, like this:
```cpp
class MockFoo : public Foo {
...
// Add the following two lines to the mock class.
- MOCK_METHOD0(Die, void());
+ MOCK_METHOD(void, Die, ());
virtual ~MockFoo() { Die(); }
};
```
-(If the name `Die()` clashes with an existing symbol, choose another
-name.) Now, we have translated the problem of testing when a `MockFoo`
-object dies to testing when its `Die()` method is called:
+(If the name `Die()` clashes with an existing symbol, choose another name.) Now,
+we have translated the problem of testing when a `MockFoo` object dies to
+testing when its `Die()` method is called:
```cpp
MockFoo* foo = new MockFoo;
@@ -2627,44 +3092,43 @@
And that's that.
-## Using Google Mock and Threads ##
+#### Using gMock and Threads {#UsingThreads}
-**IMPORTANT NOTE:** What we describe in this recipe is **ONLY** true on
-platforms where Google Mock is thread-safe. Currently these are only
-platforms that support the pthreads library (this includes Linux and Mac).
-To make it thread-safe on other platforms we only need to implement
-some synchronization operations in `"gtest/internal/gtest-port.h"`.
+In a **unit** test, it's best if you could isolate and test a piece of code in a
+single-threaded context. That avoids race conditions and dead locks, and makes
+debugging your test much easier.
-In a **unit** test, it's best if you could isolate and test a piece of
-code in a single-threaded context. That avoids race conditions and
-dead locks, and makes debugging your test much easier.
-
-Yet many programs are multi-threaded, and sometimes to test something
-we need to pound on it from more than one thread. Google Mock works
-for this purpose too.
+Yet most programs are multi-threaded, and sometimes to test something we need to
+pound on it from more than one thread. gMock works for this purpose too.
Remember the steps for using a mock:
- 1. Create a mock object `foo`.
- 1. Set its default actions and expectations using `ON_CALL()` and `EXPECT_CALL()`.
- 1. The code under test calls methods of `foo`.
- 1. Optionally, verify and reset the mock.
- 1. Destroy the mock yourself, or let the code under test destroy it. The destructor will automatically verify it.
+1. Create a mock object `foo`.
+2. Set its default actions and expectations using `ON_CALL()` and
+ `EXPECT_CALL()`.
+3. The code under test calls methods of `foo`.
+4. Optionally, verify and reset the mock.
+5. Destroy the mock yourself, or let the code under test destroy it. The
+ destructor will automatically verify it.
-If you follow the following simple rules, your mocks and threads can
-live happily together:
+If you follow the following simple rules, your mocks and threads can live
+happily together:
- * Execute your _test code_ (as opposed to the code being tested) in _one_ thread. This makes your test easy to follow.
- * Obviously, you can do step #1 without locking.
- * When doing step #2 and #5, make sure no other thread is accessing `foo`. Obvious too, huh?
- * #3 and #4 can be done either in one thread or in multiple threads - anyway you want. Google Mock takes care of the locking, so you don't have to do any - unless required by your test logic.
+* Execute your *test code* (as opposed to the code being tested) in *one*
+ thread. This makes your test easy to follow.
+* Obviously, you can do step #1 without locking.
+* When doing step #2 and #5, make sure no other thread is accessing `foo`.
+ Obvious too, huh?
+* #3 and #4 can be done either in one thread or in multiple threads - anyway
+ you want. gMock takes care of the locking, so you don't have to do any -
+ unless required by your test logic.
-If you violate the rules (for example, if you set expectations on a
-mock while another thread is calling its methods), you get undefined
-behavior. That's not fun, so don't do it.
+If you violate the rules (for example, if you set expectations on a mock while
+another thread is calling its methods), you get undefined behavior. That's not
+fun, so don't do it.
-Google Mock guarantees that the action for a mock function is done in
-the same thread that called the mock function. For example, in
+gMock guarantees that the action for a mock function is done in the same thread
+that called the mock function. For example, in
```cpp
EXPECT_CALL(mock, Foo(1))
@@ -2673,80 +3137,84 @@
.WillOnce(action2);
```
-if `Foo(1)` is called in thread 1 and `Foo(2)` is called in thread 2,
-Google Mock will execute `action1` in thread 1 and `action2` in thread
-2.
+if `Foo(1)` is called in thread 1 and `Foo(2)` is called in thread 2, gMock will
+execute `action1` in thread 1 and `action2` in thread 2.
-Google Mock does _not_ impose a sequence on actions performed in
-different threads (doing so may create deadlocks as the actions may
-need to cooperate). This means that the execution of `action1` and
-`action2` in the above example _may_ interleave. If this is a problem,
-you should add proper synchronization logic to `action1` and `action2`
-to make the test thread-safe.
+gMock does *not* impose a sequence on actions performed in different threads
+(doing so may create deadlocks as the actions may need to cooperate). This means
+that the execution of `action1` and `action2` in the above example *may*
+interleave. If this is a problem, you should add proper synchronization logic to
+`action1` and `action2` to make the test thread-safe.
+Also, remember that `DefaultValue<T>` is a global resource that potentially
+affects *all* living mock objects in your program. Naturally, you won't want to
+mess with it from multiple threads or when there still are mocks in action.
-Also, remember that `DefaultValue<T>` is a global resource that
-potentially affects _all_ living mock objects in your
-program. Naturally, you won't want to mess with it from multiple
-threads or when there still are mocks in action.
+#### Controlling How Much Information gMock Prints
-## Controlling How Much Information Google Mock Prints ##
+When gMock sees something that has the potential of being an error (e.g. a mock
+function with no expectation is called, a.k.a. an uninteresting call, which is
+allowed but perhaps you forgot to explicitly ban the call), it prints some
+warning messages, including the arguments of the function, the return value, and
+the stack trace. Hopefully this will remind you to take a look and see if there
+is indeed a problem.
-When Google Mock sees something that has the potential of being an
-error (e.g. a mock function with no expectation is called, a.k.a. an
-uninteresting call, which is allowed but perhaps you forgot to
-explicitly ban the call), it prints some warning messages, including
-the arguments of the function and the return value. Hopefully this
-will remind you to take a look and see if there is indeed a problem.
+Sometimes you are confident that your tests are correct and may not appreciate
+such friendly messages. Some other times, you are debugging your tests or
+learning about the behavior of the code you are testing, and wish you could
+observe every mock call that happens (including argument values, the return
+value, and the stack trace). Clearly, one size doesn't fit all.
-Sometimes you are confident that your tests are correct and may not
-appreciate such friendly messages. Some other times, you are debugging
-your tests or learning about the behavior of the code you are testing,
-and wish you could observe every mock call that happens (including
-argument values and the return value). Clearly, one size doesn't fit
-all.
+You can control how much gMock tells you using the `--gmock_verbose=LEVEL`
+command-line flag, where `LEVEL` is a string with three possible values:
-You can control how much Google Mock tells you using the
-`--gmock_verbose=LEVEL` command-line flag, where `LEVEL` is a string
-with three possible values:
+* `info`: gMock will print all informational messages, warnings, and errors
+ (most verbose). At this setting, gMock will also log any calls to the
+ `ON_CALL/EXPECT_CALL` macros. It will include a stack trace in
+ "uninteresting call" warnings.
+* `warning`: gMock will print both warnings and errors (less verbose); it will
+ omit the stack traces in "uninteresting call" warnings. This is the default.
+* `error`: gMock will print errors only (least verbose).
- * `info`: Google Mock will print all informational messages, warnings, and errors (most verbose). At this setting, Google Mock will also log any calls to the `ON_CALL/EXPECT_CALL` macros.
- * `warning`: Google Mock will print both warnings and errors (less verbose). This is the default.
- * `error`: Google Mock will print errors only (least verbose).
-
-Alternatively, you can adjust the value of that flag from within your
-tests like so:
+Alternatively, you can adjust the value of that flag from within your tests like
+so:
```cpp
::testing::FLAGS_gmock_verbose = "error";
```
-Now, judiciously use the right flag to enable Google Mock serve you better!
+If you find gMock printing too many stack frames with its informational or
+warning messages, remember that you can control their amount with the
+`--gtest_stack_trace_depth=max_depth` flag.
-## Gaining Super Vision into Mock Calls ##
+Now, judiciously use the right flag to enable gMock serve you better!
-You have a test using Google Mock. It fails: Google Mock tells you
-that some expectations aren't satisfied. However, you aren't sure why:
-Is there a typo somewhere in the matchers? Did you mess up the order
-of the `EXPECT_CALL`s? Or is the code under test doing something
-wrong? How can you find out the cause?
+#### Gaining Super Vision into Mock Calls
-Won't it be nice if you have X-ray vision and can actually see the
-trace of all `EXPECT_CALL`s and mock method calls as they are made?
-For each call, would you like to see its actual argument values and
-which `EXPECT_CALL` Google Mock thinks it matches?
+You have a test using gMock. It fails: gMock tells you some expectations aren't
+satisfied. However, you aren't sure why: Is there a typo somewhere in the
+matchers? Did you mess up the order of the `EXPECT_CALL`s? Or is the code under
+test doing something wrong? How can you find out the cause?
-You can unlock this power by running your test with the
-`--gmock_verbose=info` flag. For example, given the test program:
+Won't it be nice if you have X-ray vision and can actually see the trace of all
+`EXPECT_CALL`s and mock method calls as they are made? For each call, would you
+like to see its actual argument values and which `EXPECT_CALL` gMock thinks it
+matches? If you still need some help to figure out who made these calls, how
+about being able to see the complete stack trace at each mock call?
+
+You can unlock this power by running your test with the `--gmock_verbose=info`
+flag. For example, given the test program:
```cpp
+#include "gmock/gmock.h"
+
using testing::_;
using testing::HasSubstr;
using testing::Return;
class MockFoo {
public:
- MOCK_METHOD2(F, void(const string& x, const string& y));
+ MOCK_METHOD(void, F, (const string& x, const string& y));
};
TEST(Foo, Bar) {
@@ -2762,16 +3230,26 @@
if you run it with `--gmock_verbose=info`, you will see this output:
-```
-[ RUN ] Foo.Bar
+```shell
+[ RUN ] Foo.Bar
foo_test.cc:14: EXPECT_CALL(mock, F(_, _)) invoked
+Stack trace: ...
+
foo_test.cc:15: EXPECT_CALL(mock, F("a", "b")) invoked
+Stack trace: ...
+
foo_test.cc:16: EXPECT_CALL(mock, F("c", HasSubstr("d"))) invoked
+Stack trace: ...
+
foo_test.cc:14: Mock function call matches EXPECT_CALL(mock, F(_, _))...
- Function call: F(@0x7fff7c8dad40"a", @0x7fff7c8dad10"good")
+ Function call: F(@0x7fff7c8dad40"a",@0x7fff7c8dad10"good")
+Stack trace: ...
+
foo_test.cc:15: Mock function call matches EXPECT_CALL(mock, F("a", "b"))...
- Function call: F(@0x7fff7c8dada0"a", @0x7fff7c8dad70"b")
+ Function call: F(@0x7fff7c8dada0"a",@0x7fff7c8dad70"b")
+Stack trace: ...
+
foo_test.cc:16: Failure
Actual function call count doesn't match EXPECT_CALL(mock, F("c", HasSubstr("d")))...
Expected: to be called once
@@ -2779,121 +3257,119 @@
[ FAILED ] Foo.Bar
```
-Suppose the bug is that the `"c"` in the third `EXPECT_CALL` is a typo
-and should actually be `"a"`. With the above message, you should see
-that the actual `F("a", "good")` call is matched by the first
-`EXPECT_CALL`, not the third as you thought. From that it should be
-obvious that the third `EXPECT_CALL` is written wrong. Case solved.
+Suppose the bug is that the `"c"` in the third `EXPECT_CALL` is a typo and
+should actually be `"a"`. With the above message, you should see that the actual
+`F("a", "good")` call is matched by the first `EXPECT_CALL`, not the third as
+you thought. From that it should be obvious that the third `EXPECT_CALL` is
+written wrong. Case solved.
-## Running Tests in Emacs ##
+If you are interested in the mock call trace but not the stack traces, you can
+combine `--gmock_verbose=info` with `--gtest_stack_trace_depth=0` on the test
+command line.
-If you build and run your tests in Emacs, the source file locations of
-Google Mock and [Google Test](../../googletest/)
-errors will be highlighted. Just press `<Enter>` on one of them and
-you'll be taken to the offending line. Or, you can just type `C-x ``
-to jump to the next error.
+#### Running Tests in Emacs
-To make it even easier, you can add the following lines to your
-`~/.emacs` file:
+If you build and run your tests in Emacs using the `M-x google-compile` command
+(as many googletest users do), the source file locations of gMock and googletest
+errors will be highlighted. Just press `<Enter>` on one of them and you'll be
+taken to the offending line. Or, you can just type `C-x`` to jump to the next
+error.
-```
-(global-set-key "\M-m" 'compile) ; m is for make
+To make it even easier, you can add the following lines to your `~/.emacs` file:
+
+```text
+(global-set-key "\M-m" 'google-compile) ; m is for make
(global-set-key [M-down] 'next-error)
-(global-set-key [M-up] '(lambda () (interactive) (next-error -1)))
+(global-set-key [M-up] '(lambda () (interactive) (next-error -1)))
```
-Then you can type `M-m` to start a build, or `M-up`/`M-down` to move
-back and forth between errors.
+Then you can type `M-m` to start a build (if you want to run the test as well,
+just make sure `foo_test.run` or `runtests` is in the build command you supply
+after typing `M-m`), or `M-up`/`M-down` to move back and forth between errors.
-## Fusing Google Mock Source Files ##
+### Extending gMock
-Google Mock's implementation consists of dozens of files (excluding
-its own tests). Sometimes you may want them to be packaged up in
-fewer files instead, such that you can easily copy them to a new
-machine and start hacking there. For this we provide an experimental
-Python script `fuse_gmock_files.py` in the `scripts/` directory
-(starting with release 1.2.0). Assuming you have Python 2.4 or above
-installed on your machine, just go to that directory and run
-```
-python fuse_gmock_files.py OUTPUT_DIR
-```
+#### Writing New Matchers Quickly {#NewMatchers}
-and you should see an `OUTPUT_DIR` directory being created with files
-`gtest/gtest.h`, `gmock/gmock.h`, and `gmock-gtest-all.cc` in it.
-These three files contain everything you need to use Google Mock (and
-Google Test). Just copy them to anywhere you want and you are ready
-to write tests and use mocks.
+WARNING: gMock does not guarantee when or how many times a matcher will be
+invoked. Therefore, all matchers must be functionally pure. See
+[this section](#PureMatchers) for more details.
-# Extending Google Mock #
-
-## Writing New Matchers Quickly ##
-
-The `MATCHER*` family of macros can be used to define custom matchers
-easily. The syntax:
+The `MATCHER*` family of macros can be used to define custom matchers easily.
+The syntax:
```cpp
MATCHER(name, description_string_expression) { statements; }
```
-will define a matcher with the given name that executes the
-statements, which must return a `bool` to indicate if the match
-succeeds. Inside the statements, you can refer to the value being
-matched by `arg`, and refer to its type by `arg_type`.
+will define a matcher with the given name that executes the statements, which
+must return a `bool` to indicate if the match succeeds. Inside the statements,
+you can refer to the value being matched by `arg`, and refer to its type by
+`arg_type`.
-The description string is a `string`-typed expression that documents
-what the matcher does, and is used to generate the failure message
-when the match fails. It can (and should) reference the special
-`bool` variable `negation`, and should evaluate to the description of
-the matcher when `negation` is `false`, or that of the matcher's
-negation when `negation` is `true`.
+The *description string* is a `string`-typed expression that documents what the
+matcher does, and is used to generate the failure message when the match fails.
+It can (and should) reference the special `bool` variable `negation`, and should
+evaluate to the description of the matcher when `negation` is `false`, or that
+of the matcher's negation when `negation` is `true`.
-For convenience, we allow the description string to be empty (`""`),
-in which case Google Mock will use the sequence of words in the
-matcher name as the description.
+For convenience, we allow the description string to be empty (`""`), in which
+case gMock will use the sequence of words in the matcher name as the
+description.
For example:
+
```cpp
MATCHER(IsDivisibleBy7, "") { return (arg % 7) == 0; }
```
+
allows you to write
+
```cpp
// Expects mock_foo.Bar(n) to be called where n is divisible by 7.
EXPECT_CALL(mock_foo, Bar(IsDivisibleBy7()));
```
+
or,
+
```cpp
-using ::testing::Not;
-...
+ using ::testing::Not;
+ ...
+ // Verifies that two values are divisible by 7.
EXPECT_THAT(some_expression, IsDivisibleBy7());
EXPECT_THAT(some_other_expression, Not(IsDivisibleBy7()));
```
+
If the above assertions fail, they will print something like:
-```
+
+```shell
Value of: some_expression
Expected: is divisible by 7
Actual: 27
-...
+ ...
Value of: some_other_expression
Expected: not (is divisible by 7)
Actual: 21
```
-where the descriptions `"is divisible by 7"` and `"not (is divisible
-by 7)"` are automatically calculated from the matcher name
-`IsDivisibleBy7`.
-As you may have noticed, the auto-generated descriptions (especially
-those for the negation) may not be so great. You can always override
-them with a string expression of your own:
+where the descriptions `"is divisible by 7"` and `"not (is divisible by 7)"` are
+automatically calculated from the matcher name `IsDivisibleBy7`.
+
+As you may have noticed, the auto-generated descriptions (especially those for
+the negation) may not be so great. You can always override them with a `string`
+expression of your own:
+
```cpp
-MATCHER(IsDivisibleBy7, std::string(negation ? "isn't" : "is") +
- " divisible by 7") {
+MATCHER(IsDivisibleBy7,
+ absl::StrCat(negation ? "isn't" : "is", " divisible by 7")) {
return (arg % 7) == 0;
}
```
-Optionally, you can stream additional information to a hidden argument
-named `result_listener` to explain the match result. For example, a
-better definition of `IsDivisibleBy7` is:
+Optionally, you can stream additional information to a hidden argument named
+`result_listener` to explain the match result. For example, a better definition
+of `IsDivisibleBy7` is:
+
```cpp
MATCHER(IsDivisibleBy7, "") {
if ((arg % 7) == 0)
@@ -2905,156 +3381,171 @@
```
With this definition, the above assertion will give a better message:
-```
+
+```shell
Value of: some_expression
Expected: is divisible by 7
Actual: 27 (the remainder is 6)
```
-You should let `MatchAndExplain()` print _any additional information_
-that can help a user understand the match result. Note that it should
-explain why the match succeeds in case of a success (unless it's
-obvious) - this is useful when the matcher is used inside
-`Not()`. There is no need to print the argument value itself, as
-Google Mock already prints it for you.
+You should let `MatchAndExplain()` print *any additional information* that can
+help a user understand the match result. Note that it should explain why the
+match succeeds in case of a success (unless it's obvious) - this is useful when
+the matcher is used inside `Not()`. There is no need to print the argument value
+itself, as gMock already prints it for you.
-**Notes:**
+NOTE: The type of the value being matched (`arg_type`) is determined by the
+context in which you use the matcher and is supplied to you by the compiler, so
+you don't need to worry about declaring it (nor can you). This allows the
+matcher to be polymorphic. For example, `IsDivisibleBy7()` can be used to match
+any type where the value of `(arg % 7) == 0` can be implicitly converted to a
+`bool`. In the `Bar(IsDivisibleBy7())` example above, if method `Bar()` takes an
+`int`, `arg_type` will be `int`; if it takes an `unsigned long`, `arg_type` will
+be `unsigned long`; and so on.
- 1. The type of the value being matched (`arg_type`) is determined by the context in which you use the matcher and is supplied to you by the compiler, so you don't need to worry about declaring it (nor can you). This allows the matcher to be polymorphic. For example, `IsDivisibleBy7()` can be used to match any type where the value of `(arg % 7) == 0` can be implicitly converted to a `bool`. In the `Bar(IsDivisibleBy7())` example above, if method `Bar()` takes an `int`, `arg_type` will be `int`; if it takes an `unsigned long`, `arg_type` will be `unsigned long`; and so on.
- 1. Google Mock doesn't guarantee when or how many times a matcher will be invoked. Therefore the matcher logic must be _purely functional_ (i.e. it cannot have any side effect, and the result must not depend on anything other than the value being matched and the matcher parameters). This requirement must be satisfied no matter how you define the matcher (e.g. using one of the methods described in the following recipes). In particular, a matcher can never call a mock function, as that will affect the state of the mock object and Google Mock.
+#### Writing New Parameterized Matchers Quickly
-## Writing New Parameterized Matchers Quickly ##
+Sometimes you'll want to define a matcher that has parameters. For that you can
+use the macro:
-Sometimes you'll want to define a matcher that has parameters. For that you
-can use the macro:
```cpp
MATCHER_P(name, param_name, description_string) { statements; }
```
-where the description string can be either `""` or a string expression
-that references `negation` and `param_name`.
+
+where the description string can be either `""` or a `string` expression that
+references `negation` and `param_name`.
For example:
+
```cpp
MATCHER_P(HasAbsoluteValue, value, "") { return abs(arg) == value; }
```
+
will allow you to write:
+
```cpp
EXPECT_THAT(Blah("a"), HasAbsoluteValue(n));
```
+
which may lead to this message (assuming `n` is 10):
-```
+
+```shell
Value of: Blah("a")
Expected: has absolute value 10
Actual: -9
```
-Note that both the matcher description and its parameter are
-printed, making the message human-friendly.
+Note that both the matcher description and its parameter are printed, making the
+message human-friendly.
-In the matcher definition body, you can write `foo_type` to
-reference the type of a parameter named `foo`. For example, in the
-body of `MATCHER_P(HasAbsoluteValue, value)` above, you can write
-`value_type` to refer to the type of `value`.
+In the matcher definition body, you can write `foo_type` to reference the type
+of a parameter named `foo`. For example, in the body of
+`MATCHER_P(HasAbsoluteValue, value)` above, you can write `value_type` to refer
+to the type of `value`.
-Google Mock also provides `MATCHER_P2`, `MATCHER_P3`, ..., up to
-`MATCHER_P10` to support multi-parameter matchers:
+gMock also provides `MATCHER_P2`, `MATCHER_P3`, ..., up to `MATCHER_P10` to
+support multi-parameter matchers:
+
```cpp
MATCHER_Pk(name, param_1, ..., param_k, description_string) { statements; }
```
-Please note that the custom description string is for a particular
-**instance** of the matcher, where the parameters have been bound to
-actual values. Therefore usually you'll want the parameter values to
-be part of the description. Google Mock lets you do that by
-referencing the matcher parameters in the description string
+Please note that the custom description string is for a particular *instance* of
+the matcher, where the parameters have been bound to actual values. Therefore
+usually you'll want the parameter values to be part of the description. gMock
+lets you do that by referencing the matcher parameters in the description string
expression.
For example,
+
```cpp
- using ::testing::PrintToString;
- MATCHER_P2(InClosedRange, low, hi,
- std::string(negation ? "isn't" : "is") + " in range [" +
- PrintToString(low) + ", " + PrintToString(hi) + "]") {
- return low <= arg && arg <= hi;
- }
- ...
- EXPECT_THAT(3, InClosedRange(4, 6));
+using ::testing::PrintToString;
+MATCHER_P2(InClosedRange, low, hi,
+ absl::StrFormat("%s in range [%s, %s]", negation ? "isn't" : "is",
+ PrintToString(low), PrintToString(hi))) {
+ return low <= arg && arg <= hi;
+}
+...
+EXPECT_THAT(3, InClosedRange(4, 6));
```
+
would generate a failure that contains the message:
-```
+
+```shell
Expected: is in range [4, 6]
```
-If you specify `""` as the description, the failure message will
-contain the sequence of words in the matcher name followed by the
-parameter values printed as a tuple. For example,
+If you specify `""` as the description, the failure message will contain the
+sequence of words in the matcher name followed by the parameter values printed
+as a tuple. For example,
+
```cpp
MATCHER_P2(InClosedRange, low, hi, "") { ... }
...
EXPECT_THAT(3, InClosedRange(4, 6));
```
+
would generate a failure that contains the text:
-```
+
+```shell
Expected: in closed range (4, 6)
```
For the purpose of typing, you can view
+
```cpp
MATCHER_Pk(Foo, p1, ..., pk, description_string) { ... }
```
+
as shorthand for
+
```cpp
template <typename p1_type, ..., typename pk_type>
FooMatcherPk<p1_type, ..., pk_type>
Foo(p1_type p1, ..., pk_type pk) { ... }
```
-When you write `Foo(v1, ..., vk)`, the compiler infers the types of
-the parameters `v1`, ..., and `vk` for you. If you are not happy with
-the result of the type inference, you can specify the types by
-explicitly instantiating the template, as in `Foo<long, bool>(5, false)`.
-As said earlier, you don't get to (or need to) specify
-`arg_type` as that's determined by the context in which the matcher
-is used.
+When you write `Foo(v1, ..., vk)`, the compiler infers the types of the
+parameters `v1`, ..., and `vk` for you. If you are not happy with the result of
+the type inference, you can specify the types by explicitly instantiating the
+template, as in `Foo<long, bool>(5, false)`. As said earlier, you don't get to
+(or need to) specify `arg_type` as that's determined by the context in which the
+matcher is used.
-You can assign the result of expression `Foo(p1, ..., pk)` to a
-variable of type `FooMatcherPk<p1_type, ..., pk_type>`. This can be
-useful when composing matchers. Matchers that don't have a parameter
-or have only one parameter have special types: you can assign `Foo()`
-to a `FooMatcher`-typed variable, and assign `Foo(p)` to a
-`FooMatcherP<p_type>`-typed variable.
+You can assign the result of expression `Foo(p1, ..., pk)` to a variable of type
+`FooMatcherPk<p1_type, ..., pk_type>`. This can be useful when composing
+matchers. Matchers that don't have a parameter or have only one parameter have
+special types: you can assign `Foo()` to a `FooMatcher`-typed variable, and
+assign `Foo(p)` to a `FooMatcherP<p_type>`-typed variable.
-While you can instantiate a matcher template with reference types,
-passing the parameters by pointer usually makes your code more
-readable. If, however, you still want to pass a parameter by
-reference, be aware that in the failure message generated by the
-matcher you will see the value of the referenced object but not its
-address.
+While you can instantiate a matcher template with reference types, passing the
+parameters by pointer usually makes your code more readable. If, however, you
+still want to pass a parameter by reference, be aware that in the failure
+message generated by the matcher you will see the value of the referenced object
+but not its address.
You can overload matchers with different numbers of parameters:
+
```cpp
MATCHER_P(Blah, a, description_string_1) { ... }
MATCHER_P2(Blah, a, b, description_string_2) { ... }
```
-While it's tempting to always use the `MATCHER*` macros when defining
-a new matcher, you should also consider implementing
-`MatcherInterface` or using `MakePolymorphicMatcher()` instead (see
-the recipes that follow), especially if you need to use the matcher a
-lot. While these approaches require more work, they give you more
-control on the types of the value being matched and the matcher
-parameters, which in general leads to better compiler error messages
-that pay off in the long run. They also allow overloading matchers
-based on parameter types (as opposed to just based on the number of
-parameters).
+While it's tempting to always use the `MATCHER*` macros when defining a new
+matcher, you should also consider implementing `MatcherInterface` or using
+`MakePolymorphicMatcher()` instead (see the recipes that follow), especially if
+you need to use the matcher a lot. While these approaches require more work,
+they give you more control on the types of the value being matched and the
+matcher parameters, which in general leads to better compiler error messages
+that pay off in the long run. They also allow overloading matchers based on
+parameter types (as opposed to just based on the number of parameters).
-## Writing New Monomorphic Matchers ##
+#### Writing New Monomorphic Matchers
-A matcher of argument type `T` implements
-`::testing::MatcherInterface<T>` and does two things: it tests whether a
-value of type `T` matches the matcher, and can describe what kind of
-values it matches. The latter ability is used for generating readable
-error messages when expectations are violated.
+A matcher of argument type `T` implements `::testing::MatcherInterface<T>` and
+does two things: it tests whether a value of type `T` matches the matcher, and
+can describe what kind of values it matches. The latter ability is used for
+generating readable error messages when expectations are violated.
The interface looks like this:
@@ -3088,16 +3579,17 @@
};
```
-If you need a custom matcher but `Truly()` is not a good option (for
-example, you may not be happy with the way `Truly(predicate)`
-describes itself, or you may want your matcher to be polymorphic as
-`Eq(value)` is), you can define a matcher to do whatever you want in
-two steps: first implement the matcher interface, and then define a
-factory function to create a matcher instance. The second step is not
-strictly needed but it makes the syntax of using the matcher nicer.
+If you need a custom matcher but `Truly()` is not a good option (for example,
+you may not be happy with the way `Truly(predicate)` describes itself, or you
+may want your matcher to be polymorphic as `Eq(value)` is), you can define a
+matcher to do whatever you want in two steps: first implement the matcher
+interface, and then define a factory function to create a matcher instance. The
+second step is not strictly needed but it makes the syntax of using the matcher
+nicer.
-For example, you can define a matcher to test whether an `int` is
-divisible by 7 and then use it like this:
+For example, you can define a matcher to test whether an `int` is divisible by 7
+and then use it like this:
+
```cpp
using ::testing::MakeMatcher;
using ::testing::Matcher;
@@ -3106,35 +3598,36 @@
class DivisibleBy7Matcher : public MatcherInterface<int> {
public:
- virtual bool MatchAndExplain(int n, MatchResultListener* listener) const {
+ bool MatchAndExplain(int n,
+ MatchResultListener* /* listener */) const override {
return (n % 7) == 0;
}
- virtual void DescribeTo(::std::ostream* os) const {
+ void DescribeTo(::std::ostream* os) const override {
*os << "is divisible by 7";
}
- virtual void DescribeNegationTo(::std::ostream* os) const {
+ void DescribeNegationTo(::std::ostream* os) const override {
*os << "is not divisible by 7";
}
};
-inline Matcher<int> DivisibleBy7() {
+Matcher<int> DivisibleBy7() {
return MakeMatcher(new DivisibleBy7Matcher);
}
-...
+...
EXPECT_CALL(foo, Bar(DivisibleBy7()));
```
-You may improve the matcher message by streaming additional
-information to the `listener` argument in `MatchAndExplain()`:
+You may improve the matcher message by streaming additional information to the
+`listener` argument in `MatchAndExplain()`:
```cpp
class DivisibleBy7Matcher : public MatcherInterface<int> {
public:
- virtual bool MatchAndExplain(int n,
- MatchResultListener* listener) const {
+ bool MatchAndExplain(int n,
+ MatchResultListener* listener) const override {
const int remainder = n % 7;
if (remainder != 0) {
*listener << "the remainder is " << remainder;
@@ -3145,32 +3638,31 @@
};
```
-Then, `EXPECT_THAT(x, DivisibleBy7());` may general a message like this:
-```
+Then, `EXPECT_THAT(x, DivisibleBy7());` may generate a message like this:
+
+```shell
Value of: x
Expected: is divisible by 7
Actual: 23 (the remainder is 2)
```
-## Writing New Polymorphic Matchers ##
+#### Writing New Polymorphic Matchers
-You've learned how to write your own matchers in the previous
-recipe. Just one problem: a matcher created using `MakeMatcher()` only
-works for one particular type of arguments. If you want a
-_polymorphic_ matcher that works with arguments of several types (for
-instance, `Eq(x)` can be used to match a `value` as long as `value` ==
-`x` compiles -- `value` and `x` don't have to share the same type),
-you can learn the trick from `"gmock/gmock-matchers.h"` but it's a bit
-involved.
+You've learned how to write your own matchers in the previous recipe. Just one
+problem: a matcher created using `MakeMatcher()` only works for one particular
+type of arguments. If you want a *polymorphic* matcher that works with arguments
+of several types (for instance, `Eq(x)` can be used to match a *`value`* as long
+as `value == x` compiles -- *`value`* and `x` don't have to share the same
+type), you can learn the trick from `testing/base/public/gmock-matchers.h` but
+it's a bit involved.
-Fortunately, most of the time you can define a polymorphic matcher
-easily with the help of `MakePolymorphicMatcher()`. Here's how you can
-define `NotNull()` as an example:
+Fortunately, most of the time you can define a polymorphic matcher easily with
+the help of `MakePolymorphicMatcher()`. Here's how you can define `NotNull()` as
+an example:
```cpp
using ::testing::MakePolymorphicMatcher;
using ::testing::MatchResultListener;
-using ::testing::NotNull;
using ::testing::PolymorphicMatcher;
class NotNullMatcher {
@@ -3198,31 +3690,31 @@
// To construct a polymorphic matcher, pass an instance of the class
// to MakePolymorphicMatcher(). Note the return type.
-inline PolymorphicMatcher<NotNullMatcher> NotNull() {
+PolymorphicMatcher<NotNullMatcher> NotNull() {
return MakePolymorphicMatcher(NotNullMatcher());
}
+
...
EXPECT_CALL(foo, Bar(NotNull())); // The argument must be a non-NULL pointer.
```
**Note:** Your polymorphic matcher class does **not** need to inherit from
-`MatcherInterface` or any other class, and its methods do **not** need
-to be virtual.
+`MatcherInterface` or any other class, and its methods do **not** need to be
+virtual.
-Like in a monomorphic matcher, you may explain the match result by
-streaming additional information to the `listener` argument in
-`MatchAndExplain()`.
+Like in a monomorphic matcher, you may explain the match result by streaming
+additional information to the `listener` argument in `MatchAndExplain()`.
-## Writing New Cardinalities ##
+#### Writing New Cardinalities
-A cardinality is used in `Times()` to tell Google Mock how many times
-you expect a call to occur. It doesn't have to be exact. For example,
-you can say `AtLeast(5)` or `Between(2, 4)`.
+A cardinality is used in `Times()` to tell gMock how many times you expect a
+call to occur. It doesn't have to be exact. For example, you can say
+`AtLeast(5)` or `Between(2, 4)`.
-If the built-in set of cardinalities doesn't suit you, you are free to
-define your own by implementing the following interface (in namespace
-`testing`):
+If the [built-in set](#CardinalityList) of cardinalities doesn't suit you, you
+are free to define your own by implementing the following interface (in
+namespace `testing`):
```cpp
class CardinalityInterface {
@@ -3240,8 +3732,8 @@
};
```
-For example, to specify that a call must occur even number of times,
-you can write
+For example, to specify that a call must occur even number of times, you can
+write
```cpp
using ::testing::Cardinality;
@@ -3250,15 +3742,15 @@
class EvenNumberCardinality : public CardinalityInterface {
public:
- virtual bool IsSatisfiedByCallCount(int call_count) const {
+ bool IsSatisfiedByCallCount(int call_count) const override {
return (call_count % 2) == 0;
}
- virtual bool IsSaturatedByCallCount(int call_count) const {
+ bool IsSaturatedByCallCount(int call_count) const override {
return false;
}
- virtual void DescribeTo(::std::ostream* os) const {
+ void DescribeTo(::std::ostream* os) const {
*os << "called even number of times";
}
};
@@ -3266,43 +3758,78 @@
Cardinality EvenNumber() {
return MakeCardinality(new EvenNumberCardinality);
}
-...
+...
EXPECT_CALL(foo, Bar(3))
.Times(EvenNumber());
```
-## Writing New Actions Quickly ##
+#### Writing New Actions Quickly {#QuickNewActions}
-If the built-in actions don't work for you, and you find it
-inconvenient to use `Invoke()`, you can use a macro from the `ACTION*`
-family to quickly define a new action that can be used in your code as
-if it's a built-in action.
+If the built-in actions don't work for you, you can easily define your own one.
+Just define a functor class with a (possibly templated) call operator, matching
+the signature of your action.
+
+```cpp
+struct Increment {
+ template <typename T>
+ T operator()(T* arg) {
+ return ++(*arg);
+ }
+}
+```
+
+The same approach works with stateful functors (or any callable, really):
+
+```
+struct MultiplyBy {
+ template <typename T>
+ T operator()(T arg) { return arg * multiplier; }
+
+ int multiplier;
+}
+
+// Then use:
+// EXPECT_CALL(...).WillOnce(MultiplyBy{7});
+```
+
+##### Legacy macro-based Actions
+
+Before C++11, the functor-based actions were not supported; the old way of
+writing actions was through a set of `ACTION*` macros. We suggest to avoid them
+in new code; they hide a lot of logic behind the macro, potentially leading to
+harder-to-understand compiler errors. Nevertheless, we cover them here for
+completeness.
By writing
+
```cpp
ACTION(name) { statements; }
```
-in a namespace scope (i.e. not inside a class or function), you will
-define an action with the given name that executes the statements.
-The value returned by `statements` will be used as the return value of
-the action. Inside the statements, you can refer to the K-th
-(0-based) argument of the mock function as `argK`. For example:
+
+in a namespace scope (i.e. not inside a class or function), you will define an
+action with the given name that executes the statements. The value returned by
+`statements` will be used as the return value of the action. Inside the
+statements, you can refer to the K-th (0-based) argument of the mock function as
+`argK`. For example:
+
```cpp
ACTION(IncrementArg1) { return ++(*arg1); }
```
+
allows you to write
+
```cpp
... WillOnce(IncrementArg1());
```
-Note that you don't need to specify the types of the mock function
-arguments. Rest assured that your code is type-safe though:
-you'll get a compiler error if `*arg1` doesn't support the `++`
-operator, or if the type of `++(*arg1)` isn't compatible with the mock
-function's return type.
+Note that you don't need to specify the types of the mock function arguments.
+Rest assured that your code is type-safe though: you'll get a compiler error if
+`*arg1` doesn't support the `++` operator, or if the type of `++(*arg1)` isn't
+compatible with the mock function's return type.
Another example:
+
```cpp
ACTION(Foo) {
(*arg2)(5);
@@ -3311,67 +3838,75 @@
return arg0;
}
```
-defines an action `Foo()` that invokes argument #2 (a function pointer)
-with 5, calls function `Blah()`, sets the value pointed to by argument
-#1 to 0, and returns argument #0.
-For more convenience and flexibility, you can also use the following
-pre-defined symbols in the body of `ACTION`:
+defines an action `Foo()` that invokes argument #2 (a function pointer) with 5,
+calls function `Blah()`, sets the value pointed to by argument #1 to 0, and
+returns argument #0.
-| `argK_type` | The type of the K-th (0-based) argument of the mock function |
-|:----------------|:-------------------------------------------------------------|
-| `args` | All arguments of the mock function as a tuple |
-| `args_type` | The type of all arguments of the mock function as a tuple |
-| `return_type` | The return type of the mock function |
-| `function_type` | The type of the mock function |
+For more convenience and flexibility, you can also use the following pre-defined
+symbols in the body of `ACTION`:
+
+`argK_type` | The type of the K-th (0-based) argument of the mock function
+:-------------- | :-----------------------------------------------------------
+`args` | All arguments of the mock function as a tuple
+`args_type` | The type of all arguments of the mock function as a tuple
+`return_type` | The return type of the mock function
+`function_type` | The type of the mock function
For example, when using an `ACTION` as a stub action for mock function:
+
```cpp
int DoSomething(bool flag, int* ptr);
```
+
we have:
-| **Pre-defined Symbol** | **Is Bound To** |
-|:-----------------------|:----------------|
-| `arg0` | the value of `flag` |
-| `arg0_type` | the type `bool` |
-| `arg1` | the value of `ptr` |
-| `arg1_type` | the type `int*` |
-| `args` | the tuple `(flag, ptr)` |
-| `args_type` | the type `::testing::tuple<bool, int*>` |
-| `return_type` | the type `int` |
-| `function_type` | the type `int(bool, int*)` |
+Pre-defined Symbol | Is Bound To
+------------------ | ---------------------------------
+`arg0` | the value of `flag`
+`arg0_type` | the type `bool`
+`arg1` | the value of `ptr`
+`arg1_type` | the type `int*`
+`args` | the tuple `(flag, ptr)`
+`args_type` | the type `std::tuple<bool, int*>`
+`return_type` | the type `int`
+`function_type` | the type `int(bool, int*)`
-## Writing New Parameterized Actions Quickly ##
+##### Legacy macro-based parameterized Actions
-Sometimes you'll want to parameterize an action you define. For that
-we have another macro
+Sometimes you'll want to parameterize an action you define. For that we have
+another macro
+
```cpp
ACTION_P(name, param) { statements; }
```
For example,
+
```cpp
ACTION_P(Add, n) { return arg0 + n; }
```
+
will allow you to write
+
```cpp
// Returns argument #0 + 5.
... WillOnce(Add(5));
```
-For convenience, we use the term _arguments_ for the values used to
-invoke the mock function, and the term _parameters_ for the values
-used to instantiate an action.
+For convenience, we use the term *arguments* for the values used to invoke the
+mock function, and the term *parameters* for the values used to instantiate an
+action.
-Note that you don't need to provide the type of the parameter either.
-Suppose the parameter is named `param`, you can also use the
-Google-Mock-defined symbol `param_type` to refer to the type of the
-parameter as inferred by the compiler. For example, in the body of
-`ACTION_P(Add, n)` above, you can write `n_type` for the type of `n`.
+Note that you don't need to provide the type of the parameter either. Suppose
+the parameter is named `param`, you can also use the gMock-defined symbol
+`param_type` to refer to the type of the parameter as inferred by the compiler.
+For example, in the body of `ACTION_P(Add, n)` above, you can write `n_type` for
+the type of `n`.
-Google Mock also provides `ACTION_P2`, `ACTION_P3`, and etc to support
-multi-parameter actions. For example,
+gMock also provides `ACTION_P2`, `ACTION_P3`, and etc to support multi-parameter
+actions. For example,
+
```cpp
ACTION_P2(ReturnDistanceTo, x, y) {
double dx = arg0 - x;
@@ -3379,28 +3914,32 @@
return sqrt(dx*dx + dy*dy);
}
```
+
lets you write
+
```cpp
... WillOnce(ReturnDistanceTo(5.0, 26.5));
```
-You can view `ACTION` as a degenerated parameterized action where the
-number of parameters is 0.
+You can view `ACTION` as a degenerated parameterized action where the number of
+parameters is 0.
You can also easily define actions overloaded on the number of parameters:
+
```cpp
ACTION_P(Plus, a) { ... }
ACTION_P2(Plus, a, b) { ... }
```
-## Restricting the Type of an Argument or Parameter in an ACTION ##
+#### Restricting the Type of an Argument or Parameter in an ACTION
-For maximum brevity and reusability, the `ACTION*` macros don't ask
-you to provide the types of the mock function arguments and the action
-parameters. Instead, we let the compiler infer the types for us.
+For maximum brevity and reusability, the `ACTION*` macros don't ask you to
+provide the types of the mock function arguments and the action parameters.
+Instead, we let the compiler infer the types for us.
-Sometimes, however, we may want to be more explicit about the types.
-There are several tricks to do that. For example:
+Sometimes, however, we may want to be more explicit about the types. There are
+several tricks to do that. For example:
+
```cpp
ACTION(Foo) {
// Makes sure arg0 can be converted to int.
@@ -3416,31 +3955,32 @@
bool flag = param;
}
```
-where `StaticAssertTypeEq` is a compile-time assertion in Google Test
-that verifies two types are the same.
-## Writing New Action Templates Quickly ##
+where `StaticAssertTypeEq` is a compile-time assertion in googletest that
+verifies two types are the same.
-Sometimes you want to give an action explicit template parameters that
-cannot be inferred from its value parameters. `ACTION_TEMPLATE()`
-supports that and can be viewed as an extension to `ACTION()` and
-`ACTION_P*()`.
+#### Writing New Action Templates Quickly
+
+Sometimes you want to give an action explicit template parameters that cannot be
+inferred from its value parameters. `ACTION_TEMPLATE()` supports that and can be
+viewed as an extension to `ACTION()` and `ACTION_P*()`.
The syntax:
+
```cpp
ACTION_TEMPLATE(ActionName,
HAS_m_TEMPLATE_PARAMS(kind1, name1, ..., kind_m, name_m),
AND_n_VALUE_PARAMS(p1, ..., p_n)) { statements; }
```
-defines an action template that takes _m_ explicit template parameters
-and _n_ value parameters, where _m_ is between 1 and 10, and _n_ is
-between 0 and 10. `name_i` is the name of the i-th template
-parameter, and `kind_i` specifies whether it's a `typename`, an
-integral constant, or a template. `p_i` is the name of the i-th value
-parameter.
+defines an action template that takes *m* explicit template parameters and *n*
+value parameters, where *m* is in [1, 10] and *n* is in [0, 10]. `name_i` is the
+name of the *i*-th template parameter, and `kind_i` specifies whether it's a
+`typename`, an integral constant, or a template. `p_i` is the name of the *i*-th
+value parameter.
Example:
+
```cpp
// DuplicateArg<k, T>(output) converts the k-th argument of the mock
// function to type T and copies it to *output.
@@ -3448,93 +3988,104 @@
// Note the comma between int and k:
HAS_2_TEMPLATE_PARAMS(int, k, typename, T),
AND_1_VALUE_PARAMS(output)) {
- *output = T(::testing::get<k>(args));
+ *output = T(::std::get<k>(args));
}
```
To create an instance of an action template, write:
+
```cpp
- ActionName<t1, ..., t_m>(v1, ..., v_n)
+ActionName<t1, ..., t_m>(v1, ..., v_n)
```
-where the `t`s are the template arguments and the
-`v`s are the value arguments. The value argument
-types are inferred by the compiler. For example:
+
+where the `t`s are the template arguments and the `v`s are the value arguments.
+The value argument types are inferred by the compiler. For example:
+
```cpp
using ::testing::_;
...
int n;
- EXPECT_CALL(mock, Foo(_, _))
- .WillOnce(DuplicateArg<1, unsigned char>(&n));
+ EXPECT_CALL(mock, Foo).WillOnce(DuplicateArg<1, unsigned char>(&n));
```
-If you want to explicitly specify the value argument types, you can
-provide additional template arguments:
+If you want to explicitly specify the value argument types, you can provide
+additional template arguments:
+
```cpp
- ActionName<t1, ..., t_m, u1, ..., u_k>(v1, ..., v_n)
+ActionName<t1, ..., t_m, u1, ..., u_k>(v1, ..., v_n)
```
+
where `u_i` is the desired type of `v_i`.
-`ACTION_TEMPLATE` and `ACTION`/`ACTION_P*` can be overloaded on the
-number of value parameters, but not on the number of template
-parameters. Without the restriction, the meaning of the following is
-unclear:
+`ACTION_TEMPLATE` and `ACTION`/`ACTION_P*` can be overloaded on the number of
+value parameters, but not on the number of template parameters. Without the
+restriction, the meaning of the following is unclear:
```cpp
OverloadedAction<int, bool>(x);
```
-Are we using a single-template-parameter action where `bool` refers to
-the type of `x`, or a two-template-parameter action where the compiler
-is asked to infer the type of `x`?
+Are we using a single-template-parameter action where `bool` refers to the type
+of `x`, or a two-template-parameter action where the compiler is asked to infer
+the type of `x`?
-## Using the ACTION Object's Type ##
+#### Using the ACTION Object's Type
-If you are writing a function that returns an `ACTION` object, you'll
-need to know its type. The type depends on the macro used to define
-the action and the parameter types. The rule is relatively simple:
+If you are writing a function that returns an `ACTION` object, you'll need to
+know its type. The type depends on the macro used to define the action and the
+parameter types. The rule is relatively simple:
-| **Given Definition** | **Expression** | **Has Type** |
-|:---------------------|:---------------|:-------------|
-| `ACTION(Foo)` | `Foo()` | `FooAction` |
-| `ACTION_TEMPLATE(Foo, HAS_m_TEMPLATE_PARAMS(...), AND_0_VALUE_PARAMS())` | `Foo<t1, ..., t_m>()` | `FooAction<t1, ..., t_m>` |
-| `ACTION_P(Bar, param)` | `Bar(int_value)` | `BarActionP<int>` |
-| `ACTION_TEMPLATE(Bar, HAS_m_TEMPLATE_PARAMS(...), AND_1_VALUE_PARAMS(p1))` | `Bar<t1, ..., t_m>(int_value)` | `FooActionP<t1, ..., t_m, int>` |
-| `ACTION_P2(Baz, p1, p2)` | `Baz(bool_value, int_value)` | `BazActionP2<bool, int>` |
-| `ACTION_TEMPLATE(Baz, HAS_m_TEMPLATE_PARAMS(...), AND_2_VALUE_PARAMS(p1, p2))`| `Baz<t1, ..., t_m>(bool_value, int_value)` | `FooActionP2<t1, ..., t_m, bool, int>` |
-| ... | ... | ... |
+| Given Definition | Expression | Has Type |
+| ----------------------------- | ------------------- | --------------------- |
+| `ACTION(Foo)` | `Foo()` | `FooAction` |
+| `ACTION_TEMPLATE(Foo,` | `Foo<t1, ..., | `FooAction<t1, ..., |
+: `HAS_m_TEMPLATE_PARAMS(...),` : t_m>()` : t_m>` :
+: `AND_0_VALUE_PARAMS())` : : :
+| `ACTION_P(Bar, param)` | `Bar(int_value)` | `BarActionP<int>` |
+| `ACTION_TEMPLATE(Bar,` | `Bar<t1, ..., t_m>` | `FooActionP<t1, ..., |
+: `HAS_m_TEMPLATE_PARAMS(...),` : `(int_value)` : t_m, int>` :
+: `AND_1_VALUE_PARAMS(p1))` : : :
+| `ACTION_P2(Baz, p1, p2)` | `Baz(bool_value,` | `BazActionP2<bool, |
+: : `int_value)` : int>` :
+| `ACTION_TEMPLATE(Baz,` | `Baz<t1, ..., t_m>` | `FooActionP2<t1, ..., |
+: `HAS_m_TEMPLATE_PARAMS(...),` : `(bool_value,` : t_m,` `bool, int>` :
+: `AND_2_VALUE_PARAMS(p1, p2))` : `int_value)` : :
+| ... | ... | ... |
-Note that we have to pick different suffixes (`Action`, `ActionP`,
-`ActionP2`, and etc) for actions with different numbers of value
-parameters, or the action definitions cannot be overloaded on the
-number of them.
+Note that we have to pick different suffixes (`Action`, `ActionP`, `ActionP2`,
+and etc) for actions with different numbers of value parameters, or the action
+definitions cannot be overloaded on the number of them.
-## Writing New Monomorphic Actions ##
+#### Writing New Monomorphic Actions {#NewMonoActions}
While the `ACTION*` macros are very convenient, sometimes they are
-inappropriate. For example, despite the tricks shown in the previous
-recipes, they don't let you directly specify the types of the mock
-function arguments and the action parameters, which in general leads
-to unoptimized compiler error messages that can baffle unfamiliar
-users. They also don't allow overloading actions based on parameter
-types without jumping through some hoops.
+inappropriate. For example, despite the tricks shown in the previous recipes,
+they don't let you directly specify the types of the mock function arguments and
+the action parameters, which in general leads to unoptimized compiler error
+messages that can baffle unfamiliar users. They also don't allow overloading
+actions based on parameter types without jumping through some hoops.
An alternative to the `ACTION*` macros is to implement
-`::testing::ActionInterface<F>`, where `F` is the type of the mock
-function in which the action will be used. For example:
+`::testing::ActionInterface<F>`, where `F` is the type of the mock function in
+which the action will be used. For example:
```cpp
-template <typename F>class ActionInterface {
+template <typename F>
+class ActionInterface {
public:
virtual ~ActionInterface();
// Performs the action. Result is the return type of function type
// F, and ArgumentTuple is the tuple of arguments of F.
//
+
// For example, if F is int(bool, const string&), then Result would
- // be int, and ArgumentTuple would be ::testing::tuple<bool, const string&>.
+ // be int, and ArgumentTuple would be ::std::tuple<bool, const string&>.
virtual Result Perform(const ArgumentTuple& args) = 0;
};
+```
+```cpp
using ::testing::_;
using ::testing::Action;
using ::testing::ActionInterface;
@@ -3544,8 +4095,8 @@
class IncrementArgumentAction : public ActionInterface<IncrementMethod> {
public:
- virtual int Perform(const ::testing::tuple<int*>& args) {
- int* p = ::testing::get<0>(args); // Grabs the first argument.
+ int Perform(const ::std::tuple<int*>& args) override {
+ int* p = ::std::get<0>(args); // Grabs the first argument.
return *p++;
}
};
@@ -3553,8 +4104,8 @@
Action<IncrementMethod> IncrementArgument() {
return MakeAction(new IncrementArgumentAction);
}
-...
+...
EXPECT_CALL(foo, Baz(_))
.WillOnce(IncrementArgument());
@@ -3562,54 +4113,51 @@
foo.Baz(&n); // Should return 5 and change n to 6.
```
-## Writing New Polymorphic Actions ##
+#### Writing New Polymorphic Actions {#NewPolyActions}
-The previous recipe showed you how to define your own action. This is
-all good, except that you need to know the type of the function in
-which the action will be used. Sometimes that can be a problem. For
-example, if you want to use the action in functions with _different_
-types (e.g. like `Return()` and `SetArgPointee()`).
+The previous recipe showed you how to define your own action. This is all good,
+except that you need to know the type of the function in which the action will
+be used. Sometimes that can be a problem. For example, if you want to use the
+action in functions with *different* types (e.g. like `Return()` and
+`SetArgPointee()`).
-If an action can be used in several types of mock functions, we say
-it's _polymorphic_. The `MakePolymorphicAction()` function template
-makes it easy to define such an action:
+If an action can be used in several types of mock functions, we say it's
+*polymorphic*. The `MakePolymorphicAction()` function template makes it easy to
+define such an action:
```cpp
namespace testing {
-
template <typename Impl>
PolymorphicAction<Impl> MakePolymorphicAction(const Impl& impl);
-
} // namespace testing
```
-As an example, let's define an action that returns the second argument
-in the mock function's argument list. The first step is to define an
-implementation class:
+As an example, let's define an action that returns the second argument in the
+mock function's argument list. The first step is to define an implementation
+class:
```cpp
class ReturnSecondArgumentAction {
public:
template <typename Result, typename ArgumentTuple>
Result Perform(const ArgumentTuple& args) const {
- // To get the i-th (0-based) argument, use ::testing::get<i>(args).
- return ::testing::get<1>(args);
+ // To get the i-th (0-based) argument, use ::std::get(args).
+ return ::std::get<1>(args);
}
};
```
-This implementation class does _not_ need to inherit from any
-particular class. What matters is that it must have a `Perform()`
-method template. This method template takes the mock function's
-arguments as a tuple in a **single** argument, and returns the result of
-the action. It can be either `const` or not, but must be invokable
-with exactly one template argument, which is the result type. In other
-words, you must be able to call `Perform<R>(args)` where `R` is the
-mock function's return type and `args` is its arguments in a tuple.
+This implementation class does *not* need to inherit from any particular class.
+What matters is that it must have a `Perform()` method template. This method
+template takes the mock function's arguments as a tuple in a **single**
+argument, and returns the result of the action. It can be either `const` or not,
+but must be invokable with exactly one template argument, which is the result
+type. In other words, you must be able to call `Perform<R>(args)` where `R` is
+the mock function's return type and `args` is its arguments in a tuple.
-Next, we use `MakePolymorphicAction()` to turn an instance of the
-implementation class into the polymorphic action we need. It will be
-convenient to have a wrapper for this:
+Next, we use `MakePolymorphicAction()` to turn an instance of the implementation
+class into the polymorphic action we need. It will be convenient to have a
+wrapper for this:
```cpp
using ::testing::MakePolymorphicAction;
@@ -3620,41 +4168,38 @@
}
```
-Now, you can use this polymorphic action the same way you use the
-built-in ones:
+Now, you can use this polymorphic action the same way you use the built-in ones:
```cpp
using ::testing::_;
class MockFoo : public Foo {
public:
- MOCK_METHOD2(DoThis, int(bool flag, int n));
- MOCK_METHOD3(DoThat, string(int x, const char* str1, const char* str2));
+ MOCK_METHOD(int, DoThis, (bool flag, int n), (override));
+ MOCK_METHOD(string, DoThat, (int x, const char* str1, const char* str2),
+ (override));
};
-...
- MockFoo foo;
- EXPECT_CALL(foo, DoThis(_, _))
- .WillOnce(ReturnSecondArgument());
- EXPECT_CALL(foo, DoThat(_, _, _))
- .WillOnce(ReturnSecondArgument());
...
- foo.DoThis(true, 5); // Will return 5.
+ MockFoo foo;
+ EXPECT_CALL(foo, DoThis).WillOnce(ReturnSecondArgument());
+ EXPECT_CALL(foo, DoThat).WillOnce(ReturnSecondArgument());
+ ...
+ foo.DoThis(true, 5); // Will return 5.
foo.DoThat(1, "Hi", "Bye"); // Will return "Hi".
```
-## Teaching Google Mock How to Print Your Values ##
+#### Teaching gMock How to Print Your Values
-When an uninteresting or unexpected call occurs, Google Mock prints the
-argument values and the stack trace to help you debug. Assertion
-macros like `EXPECT_THAT` and `EXPECT_EQ` also print the values in
-question when the assertion fails. Google Mock and Google Test do this using
-Google Test's user-extensible value printer.
+When an uninteresting or unexpected call occurs, gMock prints the argument
+values and the stack trace to help you debug. Assertion macros like
+`EXPECT_THAT` and `EXPECT_EQ` also print the values in question when the
+assertion fails. gMock and googletest do this using googletest's user-extensible
+value printer.
This printer knows how to print built-in C++ types, native arrays, STL
-containers, and any type that supports the `<<` operator. For other
-types, it prints the raw bytes in the value and hopes that you the
-user can figure it out.
-[Google Test's advanced guide](../../googletest/docs/advanced.md#teaching-googletest-how-to-print-your-values)
-explains how to extend the printer to do a better job at
-printing your particular type than to dump the bytes.
+containers, and any type that supports the `<<` operator. For other types, it
+prints the raw bytes in the value and hopes that you the user can figure it out.
+[googletest's advanced guide](../../googletest/docs/advanced.md#teaching-googletest-how-to-print-your-values)
+explains how to extend the printer to do a better job at printing your
+particular type than to dump the bytes.
diff --git a/googlemock/docs/for_dummies.md b/googlemock/docs/for_dummies.md
index 2110531..9b15493 100644
--- a/googlemock/docs/for_dummies.md
+++ b/googlemock/docs/for_dummies.md
@@ -1,58 +1,112 @@
+## Googletest Mocking (gMock) for Dummies {#GMockForDummies}
+<!-- GOOGLETEST_CM0012 DO NOT DELETE -->
-(**Note:** If you get compiler errors that you don't understand, be sure to consult [Google Mock Doctor](frequently_asked_questions.md#how-am-i-supposed-to-make-sense-of-these-horrible-template-errors).)
+### What Is gMock?
-# What Is Google C++ Mocking Framework? #
-When you write a prototype or test, often it's not feasible or wise to rely on real objects entirely. A **mock object** implements the same interface as a real object (so it can be used as one), but lets you specify at run time how it will be used and what it should do (which methods will be called? in which order? how many times? with what arguments? what will they return? etc).
+When you write a prototype or test, often it's not feasible or wise to rely on
+real objects entirely. A **mock object** implements the same interface as a real
+object (so it can be used as one), but lets you specify at run time how it will
+be used and what it should do (which methods will be called? in which order? how
+many times? with what arguments? what will they return? etc).
-**Note:** It is easy to confuse the term _fake objects_ with mock objects. Fakes and mocks actually mean very different things in the Test-Driven Development (TDD) community:
+**Note:** It is easy to confuse the term *fake objects* with mock objects. Fakes
+and mocks actually mean very different things in the Test-Driven Development
+(TDD) community:
- * **Fake** objects have working implementations, but usually take some shortcut (perhaps to make the operations less expensive), which makes them not suitable for production. An in-memory file system would be an example of a fake.
- * **Mocks** are objects pre-programmed with _expectations_, which form a specification of the calls they are expected to receive.
+* **Fake** objects have working implementations, but usually take some
+ shortcut (perhaps to make the operations less expensive), which makes them
+ not suitable for production. An in-memory file system would be an example of
+ a fake.
+* **Mocks** are objects pre-programmed with *expectations*, which form a
+ specification of the calls they are expected to receive.
-If all this seems too abstract for you, don't worry - the most important thing to remember is that a mock allows you to check the _interaction_ between itself and code that uses it. The difference between fakes and mocks will become much clearer once you start to use mocks.
+If all this seems too abstract for you, don't worry - the most important thing
+to remember is that a mock allows you to check the *interaction* between itself
+and code that uses it. The difference between fakes and mocks shall become much
+clearer once you start to use mocks.
-**Google C++ Mocking Framework** (or **Google Mock** for short) is a library (sometimes we also call it a "framework" to make it sound cool) for creating mock classes and using them. It does to C++ what [jMock](http://www.jmock.org/) and [EasyMock](http://www.easymock.org/) do to Java.
+**gMock** is a library (sometimes we also call it a "framework" to make it sound
+cool) for creating mock classes and using them. It does to C++ what
+jMock/EasyMock does to Java (well, more or less).
-Using Google Mock involves three basic steps:
+When using gMock,
- 1. Use some simple macros to describe the interface you want to mock, and they will expand to the implementation of your mock class;
- 1. Create some mock objects and specify its expectations and behavior using an intuitive syntax;
- 1. Exercise code that uses the mock objects. Google Mock will catch any violation of the expectations as soon as it arises.
+1. first, you use some simple macros to describe the interface you want to
+ mock, and they will expand to the implementation of your mock class;
+2. next, you create some mock objects and specify its expectations and behavior
+ using an intuitive syntax;
+3. then you exercise code that uses the mock objects. gMock will catch any
+ violation to the expectations as soon as it arises.
-# Why Google Mock? #
-While mock objects help you remove unnecessary dependencies in tests and make them fast and reliable, using mocks manually in C++ is _hard_:
+### Why gMock?
- * Someone has to implement the mocks. The job is usually tedious and error-prone. No wonder people go great distances to avoid it.
- * The quality of those manually written mocks is a bit, uh, unpredictable. You may see some really polished ones, but you may also see some that were hacked up in a hurry and have all sorts of ad-hoc restrictions.
- * The knowledge you gained from using one mock doesn't transfer to the next.
+While mock objects help you remove unnecessary dependencies in tests and make
+them fast and reliable, using mocks manually in C++ is *hard*:
-In contrast, Java and Python programmers have some fine mock frameworks, which automate the creation of mocks. As a result, mocking is a proven effective technique and widely adopted practice in those communities. Having the right tool absolutely makes the difference.
+* Someone has to implement the mocks. The job is usually tedious and
+ error-prone. No wonder people go great distance to avoid it.
+* The quality of those manually written mocks is a bit, uh, unpredictable. You
+ may see some really polished ones, but you may also see some that were
+ hacked up in a hurry and have all sorts of ad hoc restrictions.
+* The knowledge you gained from using one mock doesn't transfer to the next
+ one.
-Google Mock was built to help C++ programmers. It was inspired by [jMock](http://www.jmock.org/) and [EasyMock](http://www.easymock.org/), but designed with C++'s specifics in mind. It is your friend if any of the following problems is bothering you:
+In contrast, Java and Python programmers have some fine mock frameworks (jMock,
+EasyMock, [Mox](http://wtf/mox), etc), which automate the creation of mocks. As
+a result, mocking is a proven effective technique and widely adopted practice in
+those communities. Having the right tool absolutely makes the difference.
- * You are stuck with a sub-optimal design and wish you had done more prototyping before it was too late, but prototyping in C++ is by no means "rapid".
- * Your tests are slow as they depend on too many libraries or use expensive resources (e.g. a database).
- * Your tests are brittle as some resources they use are unreliable (e.g. the network).
- * You want to test how your code handles a failure (e.g. a file checksum error), but it's not easy to cause one.
- * You need to make sure that your module interacts with other modules in the right way, but it's hard to observe the interaction; therefore you resort to observing the side effects at the end of the action, which is awkward at best.
- * You want to "mock out" your dependencies, except that they don't have mock implementations yet; and, frankly, you aren't thrilled by some of those hand-written mocks.
+gMock was built to help C++ programmers. It was inspired by jMock and EasyMock,
+but designed with C++'s specifics in mind. It is your friend if any of the
+following problems is bothering you:
-We encourage you to use Google Mock as:
+* You are stuck with a sub-optimal design and wish you had done more
+ prototyping before it was too late, but prototyping in C++ is by no means
+ "rapid".
+* Your tests are slow as they depend on too many libraries or use expensive
+ resources (e.g. a database).
+* Your tests are brittle as some resources they use are unreliable (e.g. the
+ network).
+* You want to test how your code handles a failure (e.g. a file checksum
+ error), but it's not easy to cause one.
+* You need to make sure that your module interacts with other modules in the
+ right way, but it's hard to observe the interaction; therefore you resort to
+ observing the side effects at the end of the action, but it's awkward at
+ best.
+* You want to "mock out" your dependencies, except that they don't have mock
+ implementations yet; and, frankly, you aren't thrilled by some of those
+ hand-written mocks.
- * a _design_ tool, for it lets you experiment with your interface design early and often. More iterations lead to better designs!
- * a _testing_ tool to cut your tests' outbound dependencies and probe the interaction between your module and its collaborators.
+We encourage you to use gMock as
-# Getting Started #
-Using Google Mock is easy! Inside your C++ source file, just `#include` `"gtest/gtest.h"` and `"gmock/gmock.h"`, and you are ready to go.
+* a *design* tool, for it lets you experiment with your interface design early
+ and often. More iterations lead to better designs!
+* a *testing* tool to cut your tests' outbound dependencies and probe the
+ interaction between your module and its collaborators.
-# A Case for Mock Turtles #
-Let's look at an example. Suppose you are developing a graphics program that relies on a LOGO-like API for drawing. How would you test that it does the right thing? Well, you can run it and compare the screen with a golden screen snapshot, but let's admit it: tests like this are expensive to run and fragile (What if you just upgraded to a shiny new graphics card that has better anti-aliasing? Suddenly you have to update all your golden images.). It would be too painful if all your tests are like this. Fortunately, you learned about Dependency Injection and know the right thing to do: instead of having your application talk to the drawing API directly, wrap the API in an interface (say, `Turtle`) and code to that interface:
+### Getting Started
+
+gMock is bundled with googletest.
+
+### A Case for Mock Turtles
+
+Let's look at an example. Suppose you are developing a graphics program that
+relies on a [LOGO](http://en.wikipedia.org/wiki/Logo_programming_language)-like
+API for drawing. How would you test that it does the right thing? Well, you can
+run it and compare the screen with a golden screen snapshot, but let's admit it:
+tests like this are expensive to run and fragile (What if you just upgraded to a
+shiny new graphics card that has better anti-aliasing? Suddenly you have to
+update all your golden images.). It would be too painful if all your tests are
+like this. Fortunately, you learned about
+[Dependency Injection](http://en.wikipedia.org/wiki/Dependency_injection) and know the right thing
+to do: instead of having your application talk to the system API directly, wrap
+the API in an interface (say, `Turtle`) and code to that interface:
```cpp
class Turtle {
...
- virtual ~Turtle() {}
+ virtual ~Turtle() {};
virtual void PenUp() = 0;
virtual void PenDown() = 0;
virtual void Forward(int distance) = 0;
@@ -63,65 +117,110 @@
};
```
-(Note that the destructor of `Turtle` **must** be virtual, as is the case for **all** classes you intend to inherit from - otherwise the destructor of the derived class will not be called when you delete an object through a base pointer, and you'll get corrupted program states like memory leaks.)
+(Note that the destructor of `Turtle` **must** be virtual, as is the case for
+**all** classes you intend to inherit from - otherwise the destructor of the
+derived class will not be called when you delete an object through a base
+pointer, and you'll get corrupted program states like memory leaks.)
-You can control whether the turtle's movement will leave a trace using `PenUp()` and `PenDown()`, and control its movement using `Forward()`, `Turn()`, and `GoTo()`. Finally, `GetX()` and `GetY()` tell you the current position of the turtle.
+You can control whether the turtle's movement will leave a trace using `PenUp()`
+and `PenDown()`, and control its movement using `Forward()`, `Turn()`, and
+`GoTo()`. Finally, `GetX()` and `GetY()` tell you the current position of the
+turtle.
-Your program will normally use a real implementation of this interface. In tests, you can use a mock implementation instead. This allows you to easily check what drawing primitives your program is calling, with what arguments, and in which order. Tests written this way are much more robust (they won't break because your new machine does anti-aliasing differently), easier to read and maintain (the intent of a test is expressed in the code, not in some binary images), and run _much, much faster_.
+Your program will normally use a real implementation of this interface. In
+tests, you can use a mock implementation instead. This allows you to easily
+check what drawing primitives your program is calling, with what arguments, and
+in which order. Tests written this way are much more robust (they won't break
+because your new machine does anti-aliasing differently), easier to read and
+maintain (the intent of a test is expressed in the code, not in some binary
+images), and run *much, much faster*.
-# Writing the Mock Class #
-If you are lucky, the mocks you need to use have already been implemented by some nice people. If, however, you find yourself in the position to write a mock class, relax - Google Mock turns this task into a fun game! (Well, almost.)
+### Writing the Mock Class
-## How to Define It ##
-Using the `Turtle` interface as example, here are the simple steps you need to follow:
+If you are lucky, the mocks you need to use have already been implemented by
+some nice people. If, however, you find yourself in the position to write a mock
+class, relax - gMock turns this task into a fun game! (Well, almost.)
- 1. Derive a class `MockTurtle` from `Turtle`.
- 1. Take a _virtual_ function of `Turtle` (while it's possible to [mock non-virtual methods using templates](cook_book.md#mocking-nonvirtual-methods), it's much more involved). Count how many arguments it has.
- 1. In the `public:` section of the child class, write `MOCK_METHODn();` (or `MOCK_CONST_METHODn();` if you are mocking a `const` method), where `n` is the number of the arguments; if you counted wrong, shame on you, and a compiler error will tell you so.
- 1. Now comes the fun part: you take the function signature, cut-and-paste the _function name_ as the _first_ argument to the macro, and leave what's left as the _second_ argument (in case you're curious, this is the _type of the function_).
- 1. Repeat until all virtual functions you want to mock are done.
+#### How to Define It
+
+Using the `Turtle` interface as example, here are the simple steps you need to
+follow:
+
+* Derive a class `MockTurtle` from `Turtle`.
+* Take a *virtual* function of `Turtle` (while it's possible to
+ [mock non-virtual methods using templates](#MockingNonVirtualMethods), it's
+ much more involved).
+* In the `public:` section of the child class, write `MOCK_METHOD();`
+* Now comes the fun part: you take the function signature, cut-and-paste it
+ into the macro, and add two commas - one between the return type and the
+ name, another between the name and the argument list.
+* If you're mocking a const method, add a 4th parameter containing `(const)`
+ (the parentheses are required).
+* Since you're overriding a virtual method, we suggest adding the `override`
+ keyword. For const methods the 4th parameter becomes `(const, override)`,
+ for non-const methods just `(override)`. This isn't mandatory.
+* Repeat until all virtual functions you want to mock are done. (It goes
+ without saying that *all* pure virtual methods in your abstract class must
+ be either mocked or overridden.)
After the process, you should have something like:
```cpp
-#include "gmock/gmock.h" // Brings in Google Mock.
+#include "gmock/gmock.h" // Brings in gMock.
+
class MockTurtle : public Turtle {
public:
...
- MOCK_METHOD0(PenUp, void());
- MOCK_METHOD0(PenDown, void());
- MOCK_METHOD1(Forward, void(int distance));
- MOCK_METHOD1(Turn, void(int degrees));
- MOCK_METHOD2(GoTo, void(int x, int y));
- MOCK_CONST_METHOD0(GetX, int());
- MOCK_CONST_METHOD0(GetY, int());
+ MOCK_METHOD(void, PenUp, (), (override));
+ MOCK_METHOD(void, PenDown, (), (override));
+ MOCK_METHOD(void, Forward, (int distance), (override));
+ MOCK_METHOD(void, Turn, (int degrees), (override));
+ MOCK_METHOD(void, GoTo, (int x, int y), (override));
+ MOCK_METHOD(int, GetX, (), (const, override));
+ MOCK_METHOD(int, GetY, (), (const, override));
};
```
-You don't need to define these mock methods somewhere else - the `MOCK_METHOD*` macros will generate the definitions for you. It's that simple! Once you get the hang of it, you can pump out mock classes faster than your source-control system can handle your check-ins.
+You don't need to define these mock methods somewhere else - the `MOCK_METHOD`
+macro will generate the definitions for you. It's that simple!
-**Tip:** If even this is too much work for you, you'll find the
-`gmock_gen.py` tool in Google Mock's `scripts/generator/` directory (courtesy of the [cppclean](http://code.google.com/p/cppclean/) project) useful. This command-line
-tool requires that you have Python 2.4 installed. You give it a C++ file and the name of an abstract class defined in it,
-and it will print the definition of the mock class for you. Due to the
-complexity of the C++ language, this script may not always work, but
-it can be quite handy when it does. For more details, read the [user documentation](../scripts/generator/README).
+#### Where to Put It
-## Where to Put It ##
-When you define a mock class, you need to decide where to put its definition. Some people put it in a `*_test.cc`. This is fine when the interface being mocked (say, `Foo`) is owned by the same person or team. Otherwise, when the owner of `Foo` changes it, your test could break. (You can't really expect `Foo`'s maintainer to fix every test that uses `Foo`, can you?)
+When you define a mock class, you need to decide where to put its definition.
+Some people put it in a `_test.cc`. This is fine when the interface being mocked
+(say, `Foo`) is owned by the same person or team. Otherwise, when the owner of
+`Foo` changes it, your test could break. (You can't really expect `Foo`'s
+maintainer to fix every test that uses `Foo`, can you?)
-So, the rule of thumb is: if you need to mock `Foo` and it's owned by others, define the mock class in `Foo`'s package (better, in a `testing` sub-package such that you can clearly separate production code and testing utilities), and put it in a `mock_foo.h`. Then everyone can reference `mock_foo.h` from their tests. If `Foo` ever changes, there is only one copy of `MockFoo` to change, and only tests that depend on the changed methods need to be fixed.
+So, the rule of thumb is: if you need to mock `Foo` and it's owned by others,
+define the mock class in `Foo`'s package (better, in a `testing` sub-package
+such that you can clearly separate production code and testing utilities), put
+it in a `.h` and a `cc_library`. Then everyone can reference them from their
+tests. If `Foo` ever changes, there is only one copy of `MockFoo` to change, and
+only tests that depend on the changed methods need to be fixed.
-Another way to do it: you can introduce a thin layer `FooAdaptor` on top of `Foo` and code to this new interface. Since you own `FooAdaptor`, you can absorb changes in `Foo` much more easily. While this is more work initially, carefully choosing the adaptor interface can make your code easier to write and more readable (a net win in the long run), as you can choose `FooAdaptor` to fit your specific domain much better than `Foo` does.
+Another way to do it: you can introduce a thin layer `FooAdaptor` on top of
+`Foo` and code to this new interface. Since you own `FooAdaptor`, you can absorb
+changes in `Foo` much more easily. While this is more work initially, carefully
+choosing the adaptor interface can make your code easier to write and more
+readable (a net win in the long run), as you can choose `FooAdaptor` to fit your
+specific domain much better than `Foo` does.
-# Using Mocks in Tests #
+### Using Mocks in Tests
+
Once you have a mock class, using it is easy. The typical work flow is:
- 1. Import the Google Mock names from the `testing` namespace such that you can use them unqualified (You only have to do it once per file. Remember that namespaces are a good idea and good for your health.).
- 1. Create some mock objects.
- 1. Specify your expectations on them (How many times will a method be called? With what arguments? What should it do? etc.).
- 1. Exercise some code that uses the mocks; optionally, check the result using Google Test assertions. If a mock method is called more than expected or with wrong arguments, you'll get an error immediately.
- 1. When a mock is destructed, Google Mock will automatically check whether all expectations on it have been satisfied.
+1. Import the gMock names from the `testing` namespace such that you can use
+ them unqualified (You only have to do it once per file. Remember that
+ namespaces are a good idea.
+2. Create some mock objects.
+3. Specify your expectations on them (How many times will a method be called?
+ With what arguments? What should it do? etc.).
+4. Exercise some code that uses the mocks; optionally, check the result using
+ googletest assertions. If a mock method is called more than expected or with
+ wrong arguments, you'll get an error immediately.
+5. When a mock is destructed, gMock will automatically check whether all
+ expectations on it have been satisfied.
Here's an example:
@@ -129,79 +228,68 @@
#include "path/to/mock-turtle.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"
-using ::testing::AtLeast; // #1
+
+using ::testing::AtLeast; // #1
TEST(PainterTest, CanDrawSomething) {
- MockTurtle turtle; // #2
- EXPECT_CALL(turtle, PenDown()) // #3
+ MockTurtle turtle; // #2
+ EXPECT_CALL(turtle, PenDown()) // #3
.Times(AtLeast(1));
- Painter painter(&turtle); // #4
+ Painter painter(&turtle); // #4
- EXPECT_TRUE(painter.DrawCircle(0, 0, 10));
-} // #5
-
-int main(int argc, char** argv) {
- // The following line must be executed to initialize Google Mock
- // (and Google Test) before running the tests.
- ::testing::InitGoogleMock(&argc, argv);
- return RUN_ALL_TESTS();
+ EXPECT_TRUE(painter.DrawCircle(0, 0, 10)); // #5
}
```
-As you might have guessed, this test checks that `PenDown()` is called at least once. If the `painter` object didn't call this method, your test will fail with a message like this:
+As you might have guessed, this test checks that `PenDown()` is called at least
+once. If the `painter` object didn't call this method, your test will fail with
+a message like this:
-```
+```text
path/to/my_test.cc:119: Failure
Actual function call count doesn't match this expectation:
Actually: never called;
Expected: called at least once.
+Stack trace:
+...
```
-**Tip 1:** If you run the test from an Emacs buffer, you can hit `<Enter>` on the line number displayed in the error message to jump right to the failed expectation.
+**Tip 1:** If you run the test from an Emacs buffer, you can hit <Enter> on the
+line number to jump right to the failed expectation.
-**Tip 2:** If your mock objects are never deleted, the final verification won't happen. Therefore it's a good idea to use a heap leak checker in your tests when you allocate mocks on the heap.
+**Tip 2:** If your mock objects are never deleted, the final verification won't
+happen. Therefore it's a good idea to turn on the heap checker in your tests
+when you allocate mocks on the heap. You get that automatically if you use the
+`gunit_main` library already.
-**Important note:** Google Mock requires expectations to be set **before** the mock functions are called, otherwise the behavior is **undefined**. In particular, you mustn't interleave `EXPECT_CALL()`s and calls to the mock functions.
+**Important note:** gMock requires expectations to be set **before** the mock
+functions are called, otherwise the behavior is **undefined**. In particular,
+you mustn't interleave `EXPECT_CALL()s` and calls to the mock functions.
-This means `EXPECT_CALL()` should be read as expecting that a call will occur _in the future_, not that a call has occurred. Why does Google Mock work like that? Well, specifying the expectation beforehand allows Google Mock to report a violation as soon as it arises, when the context (stack trace, etc) is still available. This makes debugging much easier.
+This means `EXPECT_CALL()` should be read as expecting that a call will occur
+*in the future*, not that a call has occurred. Why does gMock work like that?
+Well, specifying the expectation beforehand allows gMock to report a violation
+as soon as it rises, when the context (stack trace, etc) is still available.
+This makes debugging much easier.
-Admittedly, this test is contrived and doesn't do much. You can easily achieve the same effect without using Google Mock. However, as we shall reveal soon, Google Mock allows you to do _much more_ with the mocks.
+Admittedly, this test is contrived and doesn't do much. You can easily achieve
+the same effect without using gMock. However, as we shall reveal soon, gMock
+allows you to do *so much more* with the mocks.
-## Using Google Mock with Any Testing Framework ##
-If you want to use something other than Google Test (e.g. [CppUnit](http://sourceforge.net/projects/cppunit/) or
-[CxxTest](https://cxxtest.com/)) as your testing framework, just change the `main()` function in the previous section to:
-```cpp
-int main(int argc, char** argv) {
- // The following line causes Google Mock to throw an exception on failure,
- // which will be interpreted by your testing framework as a test failure.
- ::testing::GTEST_FLAG(throw_on_failure) = true;
- ::testing::InitGoogleMock(&argc, argv);
- ... whatever your testing framework requires ...
-}
-```
+### Setting Expectations
-This approach has a catch: it makes Google Mock throw an exception
-from a mock object's destructor sometimes. With some compilers, this
-sometimes causes the test program to crash. You'll still be able to
-notice that the test has failed, but it's not a graceful failure.
+The key to using a mock object successfully is to set the *right expectations*
+on it. If you set the expectations too strict, your test will fail as the result
+of unrelated changes. If you set them too loose, bugs can slip through. You want
+to do it just right such that your test can catch exactly the kind of bugs you
+intend it to catch. gMock provides the necessary means for you to do it "just
+right."
-A better solution is to use Google Test's
-[event listener API](../../googletest/docs/advanced.md#extending-googletest-by-handling-test-events)
-to report a test failure to your testing framework properly. You'll need to
-implement the `OnTestPartResult()` method of the event listener interface, but it
-should be straightforward.
+#### General Syntax
-If this turns out to be too much work, we suggest that you stick with
-Google Test, which works with Google Mock seamlessly (in fact, it is
-technically part of Google Mock.). If there is a reason that you
-cannot use Google Test, please let us know.
-
-# Setting Expectations #
-The key to using a mock object successfully is to set the _right expectations_ on it. If you set the expectations too strict, your test will fail as the result of unrelated changes. If you set them too loose, bugs can slip through. You want to do it just right such that your test can catch exactly the kind of bugs you intend it to catch. Google Mock provides the necessary means for you to do it "just right."
-
-## General Syntax ##
-In Google Mock we use the `EXPECT_CALL()` macro to set an expectation on a mock method. The general syntax is:
+In gMock we use the `EXPECT_CALL()` macro to set an expectation on a mock
+method. The general syntax is:
```cpp
EXPECT_CALL(mock_object, method(matchers))
@@ -210,11 +298,29 @@
.WillRepeatedly(action);
```
-The macro has two arguments: first the mock object, and then the method and its arguments. Note that the two are separated by a comma (`,`), not a period (`.`). (Why using a comma? The answer is that it was necessary for technical reasons.)
+The macro has two arguments: first the mock object, and then the method and its
+arguments. Note that the two are separated by a comma (`,`), not a period (`.`).
+(Why using a comma? The answer is that it was necessary for technical reasons.)
+If the method is not overloaded, the macro can also be called without matchers:
-The macro can be followed by some optional _clauses_ that provide more information about the expectation. We'll discuss how each clause works in the coming sections.
+```cpp
+EXPECT_CALL(mock_object, non-overloaded-method)
+ .Times(cardinality)
+ .WillOnce(action)
+ .WillRepeatedly(action);
+```
-This syntax is designed to make an expectation read like English. For example, you can probably guess that
+This syntax allows the test writer to specify "called with any arguments"
+without explicitly specifying the number or types of arguments. To avoid
+unintended ambiguity, this syntax may only be used for methods which are not
+overloaded
+
+Either form of the macro can be followed by some optional *clauses* that provide
+more information about the expectation. We'll discuss how each clause works in
+the coming sections.
+
+This syntax is designed to make an expectation read like English. For example,
+you can probably guess that
```cpp
using ::testing::Return;
@@ -226,97 +332,174 @@
.WillRepeatedly(Return(200));
```
-says that the `turtle` object's `GetX()` method will be called five times, it will return 100 the first time, 150 the second time, and then 200 every time. Some people like to call this style of syntax a Domain-Specific Language (DSL).
+says that the `turtle` object's `GetX()` method will be called five times, it
+will return 100 the first time, 150 the second time, and then 200 every time.
+Some people like to call this style of syntax a Domain-Specific Language (DSL).
-**Note:** Why do we use a macro to do this? It serves two purposes: first it makes expectations easily identifiable (either by `grep` or by a human reader), and second it allows Google Mock to include the source file location of a failed expectation in messages, making debugging easier.
+**Note:** Why do we use a macro to do this? Well it serves two purposes: first
+it makes expectations easily identifiable (either by `gsearch` or by a human
+reader), and second it allows gMock to include the source file location of a
+failed expectation in messages, making debugging easier.
-## Matchers: What Arguments Do We Expect? ##
-When a mock function takes arguments, we must specify what arguments we are expecting; for example:
+#### Matchers: What Arguments Do We Expect?
+
+When a mock function takes arguments, we may specify what arguments we are
+expecting, for example:
```cpp
// Expects the turtle to move forward by 100 units.
EXPECT_CALL(turtle, Forward(100));
```
-Sometimes you may not want to be too specific (Remember that talk about tests being too rigid? Over specification leads to brittle tests and obscures the intent of tests. Therefore we encourage you to specify only what's necessary - no more, no less.). If you care to check that `Forward()` will be called but aren't interested in its actual argument, write `_` as the argument, which means "anything goes":
+Oftentimes you do not want to be too specific. Remember that talk about tests
+being too rigid? Over specification leads to brittle tests and obscures the
+intent of tests. Therefore we encourage you to specify only what's necessary—no
+more, no less. If you aren't interested in the value of an argument, write `_`
+as the argument, which means "anything goes":
```cpp
using ::testing::_;
...
-// Expects the turtle to move forward.
-EXPECT_CALL(turtle, Forward(_));
+// Expects that the turtle jumps to somewhere on the x=50 line.
+EXPECT_CALL(turtle, GoTo(50, _));
```
-`_` is an instance of what we call **matchers**. A matcher is like a predicate and can test whether an argument is what we'd expect. You can use a matcher inside `EXPECT_CALL()` wherever a function argument is expected.
+`_` is an instance of what we call **matchers**. A matcher is like a predicate
+and can test whether an argument is what we'd expect. You can use a matcher
+inside `EXPECT_CALL()` wherever a function argument is expected. `_` is a
+convenient way of saying "any value".
-A list of built-in matchers can be found in the [CheatSheet](cheat_sheet.md). For example, here's the `Ge` (greater than or equal) matcher:
+In the above examples, `100` and `50` are also matchers; implicitly, they are
+the same as `Eq(100)` and `Eq(50)`, which specify that the argument must be
+equal (using `operator==`) to the matcher argument. There are many
+[built-in matchers](#MatcherList) for common types (as well as
+[custom matchers](#NewMatchers)); for example:
```cpp
using ::testing::Ge;
...
+// Expects the turtle moves forward by at least 100.
EXPECT_CALL(turtle, Forward(Ge(100)));
```
-This checks that the turtle will be told to go forward by at least 100 units.
+If you don't care about *any* arguments, rather than specify `_` for each of
+them you may instead omit the parameter list:
-## Cardinalities: How Many Times Will It Be Called? ##
-The first clause we can specify following an `EXPECT_CALL()` is `Times()`. We call its argument a **cardinality** as it tells _how many times_ the call should occur. It allows us to repeat an expectation many times without actually writing it as many times. More importantly, a cardinality can be "fuzzy", just like a matcher can be. This allows a user to express the intent of a test exactly.
+```cpp
+// Expects the turtle to move forward.
+EXPECT_CALL(turtle, Forward);
+// Expects the turtle to jump somewhere.
+EXPECT_CALL(turtle, GoTo);
+```
-An interesting special case is when we say `Times(0)`. You may have guessed - it means that the function shouldn't be called with the given arguments at all, and Google Mock will report a Google Test failure whenever the function is (wrongfully) called.
+This works for all non-overloaded methods; if a method is overloaded, you need
+to help gMock resolve which overload is expected by specifying the number of
+arguments and possibly also the [types of the arguments](#SelectOverload).
-We've seen `AtLeast(n)` as an example of fuzzy cardinalities earlier. For the list of built-in cardinalities you can use, see the [CheatSheet](cheat_sheet.md).
+#### Cardinalities: How Many Times Will It Be Called?
-The `Times()` clause can be omitted. **If you omit `Times()`, Google Mock will infer the cardinality for you.** The rules are easy to remember:
+The first clause we can specify following an `EXPECT_CALL()` is `Times()`. We
+call its argument a **cardinality** as it tells *how many times* the call should
+occur. It allows us to repeat an expectation many times without actually writing
+it as many times. More importantly, a cardinality can be "fuzzy", just like a
+matcher can be. This allows a user to express the intent of a test exactly.
- * If **neither** `WillOnce()` **nor** `WillRepeatedly()` is in the `EXPECT_CALL()`, the inferred cardinality is `Times(1)`.
- * If there are `n WillOnce()`'s but **no** `WillRepeatedly()`, where `n` >= 1, the cardinality is `Times(n)`.
- * If there are `n WillOnce()`'s and **one** `WillRepeatedly()`, where `n` >= 0, the cardinality is `Times(AtLeast(n))`.
+An interesting special case is when we say `Times(0)`. You may have guessed - it
+means that the function shouldn't be called with the given arguments at all, and
+gMock will report a googletest failure whenever the function is (wrongfully)
+called.
-**Quick quiz:** what do you think will happen if a function is expected to be called twice but actually called four times?
+We've seen `AtLeast(n)` as an example of fuzzy cardinalities earlier. For the
+list of built-in cardinalities you can use, see [here](#CardinalityList).
-## Actions: What Should It Do? ##
-Remember that a mock object doesn't really have a working implementation? We as users have to tell it what to do when a method is invoked. This is easy in Google Mock.
+The `Times()` clause can be omitted. **If you omit `Times()`, gMock will infer
+the cardinality for you.** The rules are easy to remember:
-First, if the return type of a mock function is a built-in type or a pointer, the function has a **default action** (a `void` function will just return, a `bool` function will return `false`, and other functions will return 0). In addition, in C++ 11 and above, a mock function whose return type is default-constructible (i.e. has a default constructor) has a default action of returning a default-constructed value. If you don't say anything, this behavior will be used.
+* If **neither** `WillOnce()` **nor** `WillRepeatedly()` is in the
+ `EXPECT_CALL()`, the inferred cardinality is `Times(1)`.
+* If there are *n* `WillOnce()`'s but **no** `WillRepeatedly()`, where *n* >=
+ 1, the cardinality is `Times(n)`.
+* If there are *n* `WillOnce()`'s and **one** `WillRepeatedly()`, where *n* >=
+ 0, the cardinality is `Times(AtLeast(n))`.
-Second, if a mock function doesn't have a default action, or the default action doesn't suit you, you can specify the action to be taken each time the expectation matches using a series of `WillOnce()` clauses followed by an optional `WillRepeatedly()`. For example,
+**Quick quiz:** what do you think will happen if a function is expected to be
+called twice but actually called four times?
+
+#### Actions: What Should It Do?
+
+Remember that a mock object doesn't really have a working implementation? We as
+users have to tell it what to do when a method is invoked. This is easy in
+gMock.
+
+First, if the return type of a mock function is a built-in type or a pointer,
+the function has a **default action** (a `void` function will just return, a
+`bool` function will return `false`, and other functions will return 0). In
+addition, in C++ 11 and above, a mock function whose return type is
+default-constructible (i.e. has a default constructor) has a default action of
+returning a default-constructed value. If you don't say anything, this behavior
+will be used.
+
+Second, if a mock function doesn't have a default action, or the default action
+doesn't suit you, you can specify the action to be taken each time the
+expectation matches using a series of `WillOnce()` clauses followed by an
+optional `WillRepeatedly()`. For example,
```cpp
using ::testing::Return;
...
EXPECT_CALL(turtle, GetX())
- .WillOnce(Return(100))
- .WillOnce(Return(200))
- .WillOnce(Return(300));
+ .WillOnce(Return(100))
+ .WillOnce(Return(200))
+ .WillOnce(Return(300));
```
-This says that `turtle.GetX()` will be called _exactly three times_ (Google Mock inferred this from how many `WillOnce()` clauses we've written, since we didn't explicitly write `Times()`), and will return 100, 200, and 300 respectively.
+says that `turtle.GetX()` will be called *exactly three times* (gMock inferred
+this from how many `WillOnce()` clauses we've written, since we didn't
+explicitly write `Times()`), and will return 100, 200, and 300 respectively.
```cpp
using ::testing::Return;
...
EXPECT_CALL(turtle, GetY())
- .WillOnce(Return(100))
- .WillOnce(Return(200))
- .WillRepeatedly(Return(300));
+ .WillOnce(Return(100))
+ .WillOnce(Return(200))
+ .WillRepeatedly(Return(300));
```
-says that `turtle.GetY()` will be called _at least twice_ (Google Mock knows this as we've written two `WillOnce()` clauses and a `WillRepeatedly()` while having no explicit `Times()`), will return 100 the first time, 200 the second time, and 300 from the third time on.
+says that `turtle.GetY()` will be called *at least twice* (gMock knows this as
+we've written two `WillOnce()` clauses and a `WillRepeatedly()` while having no
+explicit `Times()`), will return 100 and 200 respectively the first two times,
+and 300 from the third time on.
-Of course, if you explicitly write a `Times()`, Google Mock will not try to infer the cardinality itself. What if the number you specified is larger than there are `WillOnce()` clauses? Well, after all `WillOnce()`s are used up, Google Mock will do the _default_ action for the function every time (unless, of course, you have a `WillRepeatedly()`.).
+Of course, if you explicitly write a `Times()`, gMock will not try to infer the
+cardinality itself. What if the number you specified is larger than there are
+`WillOnce()` clauses? Well, after all `WillOnce()`s are used up, gMock will do
+the *default* action for the function every time (unless, of course, you have a
+`WillRepeatedly()`.).
-What can we do inside `WillOnce()` besides `Return()`? You can return a reference using `ReturnRef(variable)`, or invoke a pre-defined function, among [others](cheat_sheet.md#actions).
+What can we do inside `WillOnce()` besides `Return()`? You can return a
+reference using `ReturnRef(*variable*)`, or invoke a pre-defined function, among
+[others](#ActionList).
-**Important note:** The `EXPECT_CALL()` statement evaluates the action clause only once, even though the action may be performed many times. Therefore you must be careful about side effects. The following may not do what you want:
+**Important note:** The `EXPECT_CALL()` statement evaluates the action clause
+only once, even though the action may be performed many times. Therefore you
+must be careful about side effects. The following may not do what you want:
```cpp
+using ::testing::Return;
+...
int n = 100;
EXPECT_CALL(turtle, GetX())
-.Times(4)
-.WillRepeatedly(Return(n++));
+ .Times(4)
+ .WillRepeatedly(Return(n++));
```
-Instead of returning 100, 101, 102, ..., consecutively, this mock function will always return 100 as `n++` is only evaluated once. Similarly, `Return(new Foo)` will create a new `Foo` object when the `EXPECT_CALL()` is executed, and will return the same pointer every time. If you want the side effect to happen every time, you need to define a custom action, which we'll teach in the [CookBook](cook_book.md).
+Instead of returning 100, 101, 102, ..., consecutively, this mock function will
+always return 100 as `n++` is only evaluated once. Similarly, `Return(new Foo)`
+will create a new `Foo` object when the `EXPECT_CALL()` is executed, and will
+return the same pointer every time. If you want the side effect to happen every
+time, you need to define a custom action, which we'll teach in the
+[cook book](http://<!-- GOOGLETEST_CM0011 DO NOT DELETE -->).
Time for another quiz! What do you think the following means?
@@ -324,16 +507,28 @@
using ::testing::Return;
...
EXPECT_CALL(turtle, GetY())
-.Times(4)
-.WillOnce(Return(100));
+ .Times(4)
+ .WillOnce(Return(100));
```
-Obviously `turtle.GetY()` is expected to be called four times. But if you think it will return 100 every time, think twice! Remember that one `WillOnce()` clause will be consumed each time the function is invoked and the default action will be taken afterwards. So the right answer is that `turtle.GetY()` will return 100 the first time, but **return 0 from the second time on**, as returning 0 is the default action for `int` functions.
+Obviously `turtle.GetY()` is expected to be called four times. But if you think
+it will return 100 every time, think twice! Remember that one `WillOnce()`
+clause will be consumed each time the function is invoked and the default action
+will be taken afterwards. So the right answer is that `turtle.GetY()` will
+return 100 the first time, but **return 0 from the second time on**, as
+returning 0 is the default action for `int` functions.
-## Using Multiple Expectations ##
-So far we've only shown examples where you have a single expectation. More realistically, you're going to specify expectations on multiple mock methods, which may be from multiple mock objects.
+#### Using Multiple Expectations {#MultiExpectations}
-By default, when a mock method is invoked, Google Mock will search the expectations in the **reverse order** they are defined, and stop when an active expectation that matches the arguments is found (you can think of it as "newer rules override older ones."). If the matching expectation cannot take any more calls, you will get an upper-bound-violated failure. Here's an example:
+So far we've only shown examples where you have a single expectation. More
+realistically, you'll specify expectations on multiple mock methods which may be
+from multiple mock objects.
+
+By default, when a mock method is invoked, gMock will search the expectations in
+the **reverse order** they are defined, and stop when an active expectation that
+matches the arguments is found (you can think of it as "newer rules override
+older ones."). If the matching expectation cannot take any more calls, you will
+get an upper-bound-violated failure. Here's an example:
```cpp
using ::testing::_;
@@ -343,14 +538,35 @@
.Times(2);
```
-If `Forward(10)` is called three times in a row, the third time it will be an error, as the last matching expectation (#2) has been saturated. If, however, the third `Forward(10)` call is replaced by `Forward(20)`, then it would be OK, as now #1 will be the matching expectation.
+If `Forward(10)` is called three times in a row, the third time it will be an
+error, as the last matching expectation (#2) has been saturated. If, however,
+the third `Forward(10)` call is replaced by `Forward(20)`, then it would be OK,
+as now #1 will be the matching expectation.
-**Side note:** Why does Google Mock search for a match in the _reverse_ order of the expectations? The reason is that this allows a user to set up the default expectations in a mock object's constructor or the test fixture's set-up phase and then customize the mock by writing more specific expectations in the test body. So, if you have two expectations on the same method, you want to put the one with more specific matchers **after** the other, or the more specific rule would be shadowed by the more general one that comes after it.
+**Note:** Why does gMock search for a match in the *reverse* order of the
+expectations? The reason is that this allows a user to set up the default
+expectations in a mock object's constructor or the test fixture's set-up phase
+and then customize the mock by writing more specific expectations in the test
+body. So, if you have two expectations on the same method, you want to put the
+one with more specific matchers **after** the other, or the more specific rule
+would be shadowed by the more general one that comes after it.
-## Ordered vs Unordered Calls ##
-By default, an expectation can match a call even though an earlier expectation hasn't been satisfied. In other words, the calls don't have to occur in the order the expectations are specified.
+**Tip:** It is very common to start with a catch-all expectation for a method
+and `Times(AnyNumber())` (omitting arguments, or with `_` for all arguments, if
+overloaded). This makes any calls to the method expected. This is not necessary
+for methods that are not mentioned at all (these are "uninteresting"), but is
+useful for methods that have some expectations, but for which other calls are
+ok. See
+[Understanding Uninteresting vs Unexpected Calls](#uninteresting-vs-unexpected).
-Sometimes, you may want all the expected calls to occur in a strict order. To say this in Google Mock is easy:
+#### Ordered vs Unordered Calls {#OrderedCalls}
+
+By default, an expectation can match a call even though an earlier expectation
+hasn't been satisfied. In other words, the calls don't have to occur in the
+order the expectations are specified.
+
+Sometimes, you may want all the expected calls to occur in a strict order. To
+say this in gMock is easy:
```cpp
using ::testing::InSequence;
@@ -358,7 +574,7 @@
TEST(FooTest, DrawsLineSegment) {
...
{
- InSequence dummy;
+ InSequence seq;
EXPECT_CALL(turtle, PenDown());
EXPECT_CALL(turtle, Forward(100));
@@ -368,31 +584,52 @@
}
```
-By creating an object of type `InSequence`, all expectations in its scope are put into a _sequence_ and have to occur _sequentially_. Since we are just relying on the constructor and destructor of this object to do the actual work, its name is really irrelevant.
+By creating an object of type `InSequence`, all expectations in its scope are
+put into a *sequence* and have to occur *sequentially*. Since we are just
+relying on the constructor and destructor of this object to do the actual work,
+its name is really irrelevant.
-In this example, we test that `Foo()` calls the three expected functions in the order as written. If a call is made out-of-order, it will be an error.
+In this example, we test that `Foo()` calls the three expected functions in the
+order as written. If a call is made out-of-order, it will be an error.
-(What if you care about the relative order of some of the calls, but not all of them? Can you specify an arbitrary partial order? The answer is ... yes! If you are impatient, the details can be found in the [CookBook](cook_book.md#expecting-partially-ordered-calls).)
+(What if you care about the relative order of some of the calls, but not all of
+them? Can you specify an arbitrary partial order? The answer is ... yes! If you
+are impatient, the details can be found [here](#PartialOrder).)
-## All Expectations Are Sticky (Unless Said Otherwise) ##
-Now let's do a quick quiz to see how well you can use this mock stuff already. How would you test that the turtle is asked to go to the origin _exactly twice_ (you want to ignore any other instructions it receives)?
+#### All Expectations Are Sticky (Unless Said Otherwise) {#StickyExpectations}
-After you've come up with your answer, take a look at ours and compare notes (solve it yourself first - don't cheat!):
+Now let's do a quick quiz to see how well you can use this mock stuff already.
+How would you test that the turtle is asked to go to the origin *exactly twice*
+(you want to ignore any other instructions it receives)?
+
+After you've come up with your answer, take a look at ours and compare notes
+(solve it yourself first - don't cheat!):
```cpp
using ::testing::_;
+using ::testing::AnyNumber;
...
EXPECT_CALL(turtle, GoTo(_, _)) // #1
- .Times(AnyNumber());
+ .Times(AnyNumber());
EXPECT_CALL(turtle, GoTo(0, 0)) // #2
- .Times(2);
+ .Times(2);
```
-Suppose `turtle.GoTo(0, 0)` is called three times. In the third time, Google Mock will see that the arguments match expectation #2 (remember that we always pick the last matching expectation). Now, since we said that there should be only two such calls, Google Mock will report an error immediately. This is basically what we've told you in the "Using Multiple Expectations" section above.
+Suppose `turtle.GoTo(0, 0)` is called three times. In the third time, gMock will
+see that the arguments match expectation #2 (remember that we always pick the
+last matching expectation). Now, since we said that there should be only two
+such calls, gMock will report an error immediately. This is basically what we've
+told you in the [Using Multiple Expectations](#MultiExpectations) section above.
-This example shows that **expectations in Google Mock are "sticky" by default**, in the sense that they remain active even after we have reached their invocation upper bounds. This is an important rule to remember, as it affects the meaning of the spec, and is **different** to how it's done in many other mocking frameworks (Why'd we do that? Because we think our rule makes the common cases easier to express and understand.).
+This example shows that **expectations in gMock are "sticky" by default**, in
+the sense that they remain active even after we have reached their invocation
+upper bounds. This is an important rule to remember, as it affects the meaning
+of the spec, and is **different** to how it's done in many other mocking
+frameworks (Why'd we do that? Because we think our rule makes the common cases
+easier to express and understand.).
-Simple? Let's see if you've really understood it: what does the following code say?
+Simple? Let's see if you've really understood it: what does the following code
+say?
```cpp
using ::testing::Return;
@@ -403,21 +640,29 @@
}
```
-If you think it says that `turtle.GetX()` will be called `n` times and will return 10, 20, 30, ..., consecutively, think twice! The problem is that, as we said, expectations are sticky. So, the second time `turtle.GetX()` is called, the last (latest) `EXPECT_CALL()` statement will match, and will immediately lead to an "upper bound exceeded" error - this piece of code is not very useful!
+If you think it says that `turtle.GetX()` will be called `n` times and will
+return 10, 20, 30, ..., consecutively, think twice! The problem is that, as we
+said, expectations are sticky. So, the second time `turtle.GetX()` is called,
+the last (latest) `EXPECT_CALL()` statement will match, and will immediately
+lead to an "upper bound violated" error - this piece of code is not very useful!
-One correct way of saying that `turtle.GetX()` will return 10, 20, 30, ..., is to explicitly say that the expectations are _not_ sticky. In other words, they should _retire_ as soon as they are saturated:
+One correct way of saying that `turtle.GetX()` will return 10, 20, 30, ..., is
+to explicitly say that the expectations are *not* sticky. In other words, they
+should *retire* as soon as they are saturated:
```cpp
using ::testing::Return;
...
for (int i = n; i > 0; i--) {
EXPECT_CALL(turtle, GetX())
- .WillOnce(Return(10*i))
- .RetiresOnSaturation();
+ .WillOnce(Return(10*i))
+ .RetiresOnSaturation();
}
```
-And, there's a better way to do it: in this case, we expect the calls to occur in a specific order, and we line up the actions to match the order. Since the order is important here, we should make it explicit using a sequence:
+And, there's a better way to do it: in this case, we expect the calls to occur
+in a specific order, and we line up the actions to match the order. Since the
+order is important here, we should make it explicit using a sequence:
```cpp
using ::testing::InSequence;
@@ -434,14 +679,18 @@
}
```
-By the way, the other situation where an expectation may _not_ be sticky is when it's in a sequence - as soon as another expectation that comes after it in the sequence has been used, it automatically retires (and will never be used to match any call).
+By the way, the other situation where an expectation may *not* be sticky is when
+it's in a sequence - as soon as another expectation that comes after it in the
+sequence has been used, it automatically retires (and will never be used to
+match any call).
-## Uninteresting Calls ##
-A mock object may have many methods, and not all of them are that interesting. For example, in some tests we may not care about how many times `GetX()` and `GetY()` get called.
+#### Uninteresting Calls
-In Google Mock, if you are not interested in a method, just don't say anything about it. If a call to this method occurs, you'll see a warning in the test output, but it won't be a failure.
+A mock object may have many methods, and not all of them are that interesting.
+For example, in some tests we may not care about how many times `GetX()` and
+`GetY()` get called.
-# What Now? #
-Congratulations! You've learned enough about Google Mock to start using it. Now, you might want to join the [googlemock](http://groups.google.com/group/googlemock) discussion group and actually write some tests using Google Mock - it will be fun. Hey, it may even be addictive - you've been warned.
-
-Then, if you feel like increasing your mock quotient, you should move on to the [CookBook](cook_book.md). You can learn many advanced features of Google Mock there -- and advance your level of enjoyment and testing bliss.
+In gMock, if you are not interested in a method, just don't say anything about
+it. If a call to this method occurs, you'll see a warning in the test output,
+but it won't be a failure. This is called "naggy" behavior; to change, see
+[The Nice, the Strict, and the Naggy](#NiceStrictNaggy).
