auto_blacken.yml

name: auto-blacken
on: [push, pull_request]
jobs:
  # job skipper in the case of concurrent push + pull_request trigger
  pre_job:
    runs-on: ubuntu-latest
    outputs:
      should_skip: ${{steps.skip_check.outputs.should_skip}}
    steps:
      - id: skip_check
        uses: fkirc/skip-duplicate-actions@master
        with:
          concurrent_skipping: 'same_content'
          do_not_skip: '["push"]'

  # actual autoblacken
  main_job:
    name: runner / black
    needs: pre_job
    if: ${{needs.pre_job.outputs.should_skip != 'true'}}
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
        if: github.event_name == 'pull_request'
        with:
          fetch-depth: 0
          ref: ${{github.event.pull_request.head.ref}}
      - uses: actions/checkout@v2
        if: github.event_name == 'push'
        with:
          fetch-depth: 0
      - name: Check files using the black formatter
        uses: rickstaa/action-black@v1
        id: action_black
        with:
          black_args: "."
      - name: Create commit on changes
        if: steps.action_black.outputs.is_formatted == 'true'
        run: |
          git config --global user.name '${{github.actor}}'
          git config --global user.email '${{github.actor}}@users.noreply.github.com'
          git commit -am ":art: Format Python code with psf/black" -m "There appear to be some python formatting errors in ${{github.sha}}."
          git push