This tutorial builds on the Compiling FIDL tutorial. For more information on other FIDL tutorials, see the Overview.
This tutorial details how to use the LLCPP FIDL bindings by creating a unit test that you can use as a “playground” for exploring the LLCPP bindings.
This document covers how to complete the following tasks:
The example code is located in your Fuchsia checkout in //examples/fidl/llcpp/unittests/
. If you want to write all the code as you follow this tutorial, you can remove the example code:
rm -r examples/fidl/llcpp/unittests/*
Add a gtest stub to examples/fidl/llcpp/unittests/main.cc
:
#include <gtest/gtest.h> namespace { } // namespace
Define a test
target, and a package containg the test in examples/fidl/llcpp/unittests/BUILD.gn
:
{%includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/llcpp/unittests/BUILD.gn" region_tag="imports" %} test("test") { testonly = true output_name = "fidl_example_llcpp_test" sources = [ "main.cc" ] deps = [ "//third_party/googletest:gtest_main" ] } {%includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/llcpp/unittests/BUILD.gn" region_tag="package" %}
Note: The executable_path
in the package needs to match the output_name
of the test
binary. By default, the binary is placed in the test/
directory. Packages are explained further in the next tutorial
Build and run the empty test suite on a running instance of Fuchsia:
fx set core.x64 --with //examples/fidl/llcpp/unittests:fidl-example-llcpp-test fx build
In a separate terminal, run
fx qemu -kN
In a separate terminal, run
fx serve
Back in the original terminal (with fx build
), run
fx test -vo fidl-example-llcpp-test
You should see test output indicating that zero tests have run, since no tests have been added yet.
For each FIDL library declaration, including the one in Compiling FIDL, C++ library containing LLCPP bindings code for that library is generated under the original target name appended with _llcpp
.
Add a dependency on the LLCPP bindings by referencing this target. The new test
target should look like:
{%includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/llcpp/unittests/BUILD.gn" region_tag="test" %}
(Optional) To view the newly generated bindings:
fx build
.out/default/fidling/gen/examples/fidl/fuchsia.examples/fuchsia/examples
, where the generated files are located. You may need to change out/default
if you have set a different build output directory. You can check your build output directory with cat .fx-build-dir
.For more information on how to find generated bindings code, see Viewing generated bindings code.
To include the bindings, add the following include statement to the top of examples/fidl/llcpp/unittests/main.cc
{%includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/llcpp/unittests/main.cc" region_tag="include" %}
You can now write some tests by referring to the generated code. For more information on the bindings, see LLCPP Bindings Reference.
To get started, you can also use some example code. You can add this inside the anonymous namespace in main.cc
:
{%includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/llcpp/unittests/main.cc" region_tag="bits" %} {%includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/llcpp/unittests/main.cc" region_tag="enums" %} {%includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/llcpp/unittests/main.cc" region_tag="structs" %} {%includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/llcpp/unittests/main.cc" region_tag="unions" %} {%includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/llcpp/unittests/main.cc" region_tag="tables" %}
To rebuild and rerun the tests, run:
fx test -vo fidl_crates_test