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FIDL Dart packages

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 FIDL from Dart by creating a unit test that you can use as a "playground" for exploring the Dart bindings.

This document covers how to complete the following tasks:

The example code is located in your Fuchsia checkout in //examples/fidl/dart/fidl_packages/. If you want to write all the code as you follow this tutorial, you can remove the example code:

rm -r examples/fidl/dart/fidl_packages/*

Relative paths in the rest of the tutorial will be relative to this directory.

Write a Dart host test {#write-a-dart-test}

  1. Add a sample test to test/types_test.dart:
import 'package:test/test.dart';

void main() {
  test('sample', () {
    expect(1 + 1, equals(2));
  });
}
  1. Define a dart_test and then create a depencency on the test through the $host_toolchain. To do this, add the following to BUILD.gn:
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/dart/fidl_packages/BUILD.gn" region_tag="imports" %}

 dart_test("fidl-example-dart-test") {
   sources = [ "types_test.dart" ]
   deps = [ "//third_party/dart-pkg/pub/test" ]
 }

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/dart/fidl_packages/BUILD.gn" region_tag="group" %}

Note: dart_test will look for source files in the test dir by default, so types_test.dart is specified relative to that directory. A different directory can be used by specifying a value for source_dir.

  1. Create an empty pubspec file at pubspec.yaml:
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/dart/fidl_packages/pubspec.yaml" %}
  1. Run the empty test suite:
fx set core.x64 --with //examples/fidl/dart/fidl_packages
fx test -vo fidl-example-dart-test

You should see test output for the sample test that was added.

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

For each FIDL library declaration, including the one in [Compiling FIDL][fidl-intro], a Dart package containing bindings code for that library is generated under the original target name.

Add a dependency on the Dart bindings by referencing this generated crate. The new dart_test target should look like:

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/dart/fidl_packages/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/dartlang/gen/examples/fidl/fuchsia.examples/fuchsia.examples_package. The code is generated into lib/fidl_async.dart and lib/fidl_test.dart. 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].

Import the FIDL Dart package into your project {#include-dart-bindings}

To import the package, add the following import statement to the top of the types_test.dart file:

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/dart/fidl_packages/test/types_test.dart" region_tag="import" adjust_indentation="auto" %}

In the Fuchsia tree, FIDL package imports are often aliased to fidl_[library] for readability.

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 [Dart Bindings Reference][bindings-ref].

To get started, you can also use some example code. You can add the following tests inside main():

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/dart/fidl_packages/test/types_test.dart" region_tag="bits" adjust_indentation="auto" %}

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/dart/fidl_packages/test/types_test.dart" region_tag="enums" adjust_indentation="auto" %}

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/dart/fidl_packages/test/types_test.dart" region_tag="structs" adjust_indentation="auto" %}

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/dart/fidl_packages/test/types_test.dart" region_tag="unions" adjust_indentation="auto" %}

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="examples/fidl/dart/fidl_packages/test/types_test.dart" region_tag="tables" adjust_indentation="auto" %}

To rebuild and rerun the tests, run:

fx test -vo fidl-example-dart-test

package-layout /development/languages/fidl/guides/generated-code.md#dart bindings-reffidl-introoverview

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