name: Check CHANGELOG.md

on:
  push:
    branches: [ master ]
  pull_request:
    branches: [ master ]

jobs:
  check_changelog:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: Check for CHANGELOG.md
        run: |
          if ! git diff --name-only HEAD^ | grep -q "^CHANGELOG.md$"; then
            echo "ERROR: CHANGELOG.md not modified in this pull request"
            exit 1
          fi