A GitHub Action to enable running pytest --last-failed in your CI

This composite GitHub Action makes use of GitHub's Cache action to enable pytest's --last-failed functionality for your CI workflow to speed up testing in PRs, without compromising on having the full test suite running and passing before a merge.

This action requires that Python is already setup and that pytest is already installed in the environment.

Then, if your workflow currently contains a pytest step as follows:

  - name: pytest
    run: pytest --my --pytest --arguments

you can replace it with:

  - name pytest
    uses: sjvrijn/pytest-last-failed@v1
    with:
      pytest-args: '--my --pytest --arguments'

That's all!

For any first run, it will always run the entire test suite. On subsequent runs, if the pytest cache indicates any last-failed tests, it will run pytest --last-failed instead. If that run succeded, i.e., all previously failed tests now pass again, then the whole test suite will be run again.

Or in pseudo-code:

if not cache.has_last_failed_entries():
    pytest --cache-clear $PYTEST-ARGS
else:
    result = $( pytest --last-failed $PYTEST-ARGS )

    if result == 'success':
        pytest --cache-clear $PYTEST-ARGS