name: Prevent yarn.lock changes in PRs
on: [pull_request]

jobs:
  main:
    name: Prevent yarn.lock changes in PRs
    runs-on: ubuntu-latest
    steps:
      - id: file_changes
        uses: trilom/file-changes-action@ce38c8ce2459ca3c303415eec8cb0409857b4272
      - name: Check for yarn.lock changes
        run: |
          cat $HOME/files.json | jq -e '.[] | test("yarn\\.lock$") | not' \
            || (echo "Changes to yarn.lock files aren't allowed in PRs." && exit 1)