pr-title.yml

name: Check the pull request title

on:
  pull_request:
    types: [opened, edited, reopened, synchronize]

jobs:
  check:
    runs-on: ubuntu-latest
    steps:
    - name : Check the PR title
      env:
        TITLE: ${{ github.event.pull_request.title }}
      run: |
        # Check that PR is of the form `<subsystem>: <lowercase message>`

        url='https://docs.scion.org/en/latest/dev/git.html#good-commit-messages'
        if [[ ! "$TITLE" =~ ^[a-z0-9,/-]*:[[:space:]] ]]; then
          echo '::error::The PR title should start with `<substystem>: `. See '"$url"
          exit 1
        fi
        # Title should be lower case; initialisms and identifiers still occur occasionally and should be allowed.
        # -> enforce only the first word
        if [[ ! "$TITLE" =~ ^[a-z0-9,/-]*:[[:space:]][a-z] ]]; then
          echo '::error::The PR title should be lower case (enforced on first letter). See '"$url"
          exit 1
        fi
        if [[ $TITLE =~ \.[[:space:]]*$ ]]; then
          echo '::error::The PR title should not end with a ".". See '"$url"
          exit 1
        fi