pr-validation.yaml

name: Pull Request Validation
"on":
  pull_request:
    types: [opened, synchronize, reopened, edited]
    branches: [main]
jobs:
  # Count the number of commits in a pull request. This can be
  # disabled by adding a trailer line of the following form to the
  # pull request message:
  #
  #    Disable-Check: commit-count
  #
  # The check is case-insensitive and ignores other contents on the
  # line as well, so it is possible to add several different checks if
  # that is necessary.
  #
  # It is assumed that the trailer is following RFC2822 conventions,
  # but this is currently not enforced.
  count_commits:
    name: Enforce single commit pull request
    runs-on: ubuntu-latest
    steps:
    - name: Checkout source
      uses: actions/checkout@v3
      with:
        ref: ${{ github.event.pull_request.head.sha }}
        fetch-depth: 0
    - name: Dump GitHub context (for debugging)
      env:
        GITHUB_CONTEXT: ${{ toJSON(github) }}
      run: |
        echo "GITHUB_CONTEXT: $GITHUB_CONTEXT"
    - name: Check number of commits
      shell: bash --norc --noprofile {0}
      env:
        BODY: ${{ github.event.pull_request.body }}
      run: |
        echo "$BODY" | egrep -qsi '^disable-check:.*\<commit-count\>'
        if [[ $? -ne 0 ]]; then
          base=${{ github.event.pull_request.base.sha }}
          head=${{ github.event.pull_request.head.sha }}
          count=`git rev-list --count $base..$head`
          if [[ "$count" -ne 1 ]]; then
            echo "Found $count commits in pull request (there should be only one):"
            git log --format=format:'- %h %s' $base..$head
            echo
            echo "To disable commit count, add this trailer to pull request message:"
            echo
            echo "Disable-check: commit-count"
            echo
            echo "Trailers follow RFC2822 conventions, so no whitespace"
            echo "before field name and the check is case-insensitive for"
            echo "both the field name and the field body."
            exit 1
          fi
        fi