Flutter Tools

This section of the Flutter repository contains the command line developer tools for building Flutter applications.

Working on Flutter Tools

Be sure to follow the instructions on CONTRIBUTING.md to set up your development environment. Further, familiarize yourself with the style guide, which we follow.

Setting up

First, ensure that the Dart SDK and other necessary artifacts are available by invoking the Flutter Tools wrapper script. In this directory run:

$ ../../bin/flutter --version

Running the Tool

To run Flutter Tools from source, in this directory run:

$ ../../bin/cache/dart-sdk/bin/dart bin/flutter_tools.dart

followed by command line arguments, as usual.

Running the analyzer

To run the analyzer on Flutter Tools, in this directory run:

$ ../../bin/flutter analyze

Writing tests

As with other parts of the Flutter repository, all changes in behavior must be tested. Tests live under the test/ subdirectory.

• Hermetic unit tests of tool internals go under test/general.shard.
• Tests of tool commands go under test/commands.shard. Hermetic tests go under its hermetic/ subdirectory. Non-hermetic tests go under its permeable sub-directory.
• Integration tests (e.g. tests that run the tool in a subprocess) go under test/integration.shard.

In general, the tests for the code in a file called file.dart should go in a file called file_test.dart in the subdirectory that matches the behavior of the test.

We measure test coverage post-submit. A change that deletes code might decrease test coverage, however most changes that add new code should aim to increase coverage. In particular the coverage of the diff should be close to the average coverage, and should ideally be better.

Running the tests

To run the tests in the test/ directory, first ensure that there are no connected devices. Then, in this directory run:

$ ../../bin/cache/dart-sdk/bin/pub run test

The tests in test/integration.shard are slower to run than the tests in test/general.shard. To run only the tests in test/general.shard, in this directory run:

$ ../../bin/cache/dart-sdk/bin/pub run test test/general.shard

To run the tests in a specific file, run:

$ ../../bin/cache/dart-sdk/bin/pub run test test/general.shard/utils_test.dart

When running all of the tests, it is a bit faster to use build_runner. First, set FLUTTER_ROOT to the root of your Flutter checkout. Then, in this directory run:

$ ../../bin/cache/dart-sdk/bin/pub run build_runner test

This is what we do in the continuous integration bots.

Forcing snapshot regeneration

To force the Flutter Tools snapshot to be regenerated, delete the following files:

$ rm ../../bin/cache/flutter_tools.stamp ../../bin/cache/flutter_tools.snapshot