This tutorial builds on the HLCPP getting started tutorials.
This tutorial walks through the process of writing a test for the Echo.EchoString
method. This tutorial shows you how to use the two utilities available for testing FIDL protocols implemented in HLCPP:
gtest
test loop fixture sys::testing::ComponentContextProvider
.fidl_test_base.h
file provided by the HLCPP bindingsIf you want to write the code yourself, delete the following directories:
rm -r examples/fidl/hlcpp/testing/*
The test will be written in examples/fidl/hlcpp/testing/main.cc
.
To set up dependencies:
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/hlcpp/testing/main.cc" region_tag="includes" %}
examples/fidl/hlcpp/testing/BUILD.gn
:{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/hlcpp/testing/BUILD.gn" %}
To create a server implementation:
Add an implementation for the Echo
protocol that is tested:
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/hlcpp/testing/main.cc" region_tag="impl" %}
Rather than inheriting from fuchsia::examples::Echo
, this implementation inherits from the corresponding test base class. This means that the implementation only needs to override the methods that are being tested (in this case, EchoString
), as well as the NotImplemented_
method, which is called if any of the request handler methods that are not overridden get called.
Create a test class that wraps the logic of publishing the echo protocol:
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/hlcpp/testing/main.cc" region_tag="wrapper" %}
This is similar to the code that is explained in the server tutorial, but the fidl::Binding
is owned by the class. This makes the binding's destructor get called when the class is destroyed. This enables the code to publish the echo protocol on each test case given a new instance of the test component context.
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/hlcpp/testing/main.cc" region_tag="fixture" %}
The test fixture does the following:
ComponentContextProvider
. Each test, it uses it to create a new test context, and binds the Echo implementation to it using the EchoServerInstance
class.GetProxy()
method initializes a proxy to the current test component context and returns it.This is an example test that can you can write with the test fixture:
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/hlcpp/testing/main.cc" region_tag="test" %}
To run the test:
Configure your GN build to include the test:
fx set core.x64 --with //examples/fidl/hlcpp/testing
Run the test:
fx test -vo example-hlcpp-protocol-test
You should see the test output indicating a success.
gtest::TestLoopFixture
removes the need for boilerplate async loop setup code. Each test case can simply call RunLoopUntilIdle()
instead of manually managing an async::Loop
.ComponentContextProvider
makes it easy to mock the component context during a test. This is useful to e.g. provide specific capabilities to the a component.