.github/workflows/check-api-compatibility.yml

name: Check API compatibility

on: pull_request

jobs:
  check-api-compatibility:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout old version
        uses: actions/checkout@v3
        with:
          ref: ${{ github.event.pull_request.base.sha }}
          path: 'gson-old-japicmp'

      - name: Set up JDK 11
        uses: actions/setup-java@v3
        with:
          distribution: 'temurin'
          java-version: '11'
          cache: 'maven'

      - name: Build old version
        run: |
          cd gson-old-japicmp
          # Set dummy version
          mvn --batch-mode --no-transfer-progress org.codehaus.mojo:versions-maven-plugin:2.11.0:set -DnewVersion=JAPICMP-OLD
          # Install artifacts with dummy version in local repository; used later by Maven plugin for comparison
          mvn --batch-mode --no-transfer-progress install -DskipTests

      - name: Checkout new version
        uses: actions/checkout@v3

      - name: Check API compatibility
        id: check-compatibility
        run: |
          mvn --batch-mode --fail-at-end --no-transfer-progress package japicmp:cmp -DskipTests

      - name: Upload API differences artifacts
        uses: actions/upload-artifact@v3
        # Run on workflow success (in that case differences report might include added methods and classes)
        # or when API compatibility check failed
        if: success() || ( failure() && steps.check-compatibility.outcome == 'failure' )
        with:
          name: api-differences
          path: |
            **/japicmp/default-cli.html
            **/japicmp/default-cli.diff
          # Plugin should always have created report files (though they might be empty)
          if-no-files-found: error