backstop-regression-testing.yml

name: Backstop.js regression testing
on:
  pull_request:

permissions:           # https://github.com/EnricoMi/publish-unit-test-result-action/issues/161#issuecomment-905921434
  contents: read
  issues: write
  pull-requests: write
  checks: write

jobs:
  backstop:
    runs-on: ubuntu-latest
    strategy:
      max-parallel: 1
      matrix:
        ref:
          - ${{ github.base_ref }}
          - ${{ github.head_ref }}
    steps:
      - uses: actions/checkout@v2
        with:
          ref: ${{ matrix.ref }}

      - name: Compute variables
      # See https://docs.github.com/en/actions/reference/workflow-commands-for-github-actions#environment-files
        run: |
          exec >> $GITHUB_ENV
          if [ "$current_ref" = "$base_ref" ]; then
            echo backstop_verb=reference
          else
            echo backstop_verb=test
          fi
        env:
          current_ref: ${{ matrix.ref }}
          base_ref: ${{ github.base_ref }}

      - uses: actions/setup-node@v3
        with:
          cache: yarn
          node-version: 16

      # Work around https://github.com/yarnpkg/yarn/issues/4890
      - name: Install dependencies
        run: yarn --frozen-lockfile --network-timeout 1000000

      - if: ${{ env.backstop_verb == 'test' }}
        name: Download baseline Backstop results from previous run
        uses: actions/download-artifact@v2
        with:
          name: backstop-report
          path: tests/backstop

      - name: Run Backstop
        run: |
          yarn start &
          for retry in $(seq 1 6); do if ! curl --silent -o /dev/null http://localhost:3000/ ; then sleep 10; fi; done
          node scripts/make_backstop_json.js
          npx backstop ${{ env.backstop_verb }} --config=build/backstop.json || true

      - uses: actions/upload-artifact@v2
        with:
          name: backstop-report
          path: tests/backstop

      - if: ${{ env.backstop_verb == 'test' }}
        uses: EnricoMi/publish-unit-test-result-action@v1
        with:
          fail_on: nothing
          files: tests/backstop/ci_report/xunit.xml