This section of the Flutter repository contains the command line developer tools for building Flutter applications.
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.
First, ensure that the Dart SDK and other necessary artifacts are available by invoking the Flutter Tools wrapper script. In this directory run:
$ flutter --version
To run Flutter Tools from source, in this directory run:
$ dart bin/flutter_tools.dart
followed by command-line arguments, as usual.
To run the analyzer on Flutter Tools, in this directory run:
$ flutter analyze
As with other parts of the Flutter repository, all changes in behavior must be tested. Tests live under the
Hermetic unit tests of tool internals go under
test/general.shard and must run in significantly less than two seconds.
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. Avoid adding tests here and prefer writing either a unit test or a full integration test.
Integration tests (e.g. tests that run the tool in a subprocess) go under
Slow web-related tests go in the
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.
dart_test.yaml file configures the timeout for these tests to be 15 minutes. The
test.dart script that is used in CI overrides this to two seconds for the
test/general.shard directory, to catch behaviour that is unexpectedly slow.
Please avoid setting any other timeouts.
The integration tests can be configured to use a specific local engine variant by setting the
FLUTTER_LOCAL_ENGINE environment variable to the name of the local engine (e.g. “android_debug_unopt”). If the local engine build requires a source path, this can be provided by setting the
FLUTTER_LOCAL_ENGINE_SRC_PATH environment variable. This second variable is not necessary if the
engine checkouts are in adjacent directories.
export FLUTTER_LOCAL_ENGINE=android_debug_unopt flutter test test/integration.shard/some_test_case
To run all of the unit tests:
$ flutter test test/general.shard
The tests in
test/integration.shard are slower to run than the tests in
test/general.shard. Depending on your development computer, you might want to limit concurrency. Generally it is easier to run these on CI, or to manually verify the behavior you are changing instead of running the test.
The integration tests also require the
FLUTTER_ROOT environment variable to be set. The full invocation to run everything might therefore look something like:
$ export FLUTTER_ROOT=~/path/to/flutter-sdk $ flutter test --concurrency 1
This may take some time (on the order of an hour). The unit tests alone take much less time (on the order of a minute).
You can run the tests in a specific file, e.g.:
$ flutter test test/general.shard/utils_test.dart
To force the Flutter Tools snapshot to be regenerated, delete the following files:
$ rm ../../bin/cache/flutter_tools.stamp ../../bin/cache/flutter_tools.snapshot