name: Check pull request target
on:
  pull_request:
    types:
      - opened
      - reopened
      - synchronize
    branches:
      - master
jobs:
  check-branches:
    runs-on: ubuntu-latest
    steps:
      - name: Check target branch
        run: |
          if [ ${{ github.head_ref }} != "dev" ]; then
            echo "Only pull requests from dev branch are only allowed to be merged into master branch."
            exit 1
          fi