Git Hooks

The behavior of git commands can be customized through the use of "hooks". These hooks are described in detail in git's documentation.

git looks for an executables by name in the directory specified by the core.hooksPath git config setting. The script setup.py here points core.hooksPath at this directory. It runs during a gclient sync or a gclient runhooks.

The hooks here are implemented in Dart by the program with entrypoint bin/main.dart in this directory. The commands of the program are the implementation of the different hooks, for example bin/main.dart pre-push .... Since the Dart program itself isn't an executable, these commands are invoked by small Python wrapper scripts. These wrapper scripts have the names that git will look for.

pre-push

This hooks runs when pushing commits to a remote branch, for example to create or update a pull request: git push origin my-local-branch.

The pre-push hook runs ci/lint.sh and ci/format.sh. ci/analyze.sh and ci/licenses.sh are more expensive and are not run.

Adding new pre-push checks

Since the pre-push checks run on every git push, they should run quickly. New checks can be added by modifying the run() method of the PrePushCommand class in lib/src/pre_push_command.dart.

Creating a new hook

1. Check the git documentation, and copy pre-push into a script with the right name.
2. Make sure the script has the executable bit set (chmod +x <script>).
3. Add a new Command implementation under lib/src. Give the new Command the same name as the new hook.
4. Add the new Command to the CommandRunner in lib/githooks.dart.
5. Make sure the script from step (1) is passing the new command to the Dart program.