LLCPP FIDL library

Prerequisites

This tutorial builds on the [Compiling FIDL][fidl-intro] tutorial. For more information on other FIDL tutorials, see the [Overview][overview].

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:

• Write a C++ FIDL LLCPP test.
• Add the LLCPP bindings of a FIDL library as a build dependency.
• Import the LLCPP bindings into your code.
• Inspect and use the generated bindings code.

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/*

Write a C++ FIDL LLCPP test {#write-a-cpp-test}

1. Add a gtest stub to examples/fidl/llcpp/unittests/main.cc:

#include <gtest/gtest.h>

namespace {

} // namespace

1. Define a test target, and a package containing 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 = [ "//src/lib/fxl/test:gtest_main" ]
}

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/llcpp/unittests/BUILD.gn" region_tag="package" %}

1. 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.

Add the LLCPP FIDL bindings as a dependency {#add-dependency}

For each FIDL library declaration, including the one in [Compiling FIDL][fidl-intro], 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:

1. Rebuild using fx build.
2. Change to the generated files directory: 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][generated-code].

Include the LLCPP bindings in your C++ code {#include-llcpp-bindings}

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" %}

Inspect and use the generated bindings code {#inspect-user-generated-bindings}

You can now write some tests by referring to the generated code. For more information on the bindings, see [LLCPP Bindings Reference][bindings-ref].

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-example-llcpp-test

generated-code /reference/fidl/bindings/llcpp-bindings.md fidl-introoverviewserver-tut

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最后更新: 2022 年 12 月 31 日（Saturday） 21:06 CST