coverage_badge.yaml

name: Coverage badge

# Regenerates the coverage badge (coverage.json) on a daily schedule and opens
# a PR if the value has changed. This replaces the previous approach of pushing
# the badge directly to master from CI, which raced/force-pushed and failed CI.
on:
  schedule:
    # 13:00 UTC daily.
    - cron: '0 13 * * *'
  workflow_dispatch:

jobs:
  update-coverage-badge:
    runs-on: ubuntu-latest
    permissions:
      contents: write
      pull-requests: write
    steps:
      - name: Setup Java JDK
        uses: actions/setup-java@v4
        with:
          distribution: 'temurin'
          java-version: '21'
      - name: Setup Go environment
        uses: actions/setup-go@v5
        with:
          go-version: ^1.17
        id: go
      - name: Setup Bazelisk
        run: go install github.com/bazelbuild/bazelisk@latest && export PATH=$PATH:$(go env GOPATH)/bin
      - uses: actions/checkout@v4
      - name: Run bazel-diff tests with coverage
        env:
          USE_BAZEL_VERSION: '9.x'
        run: ~/go/bin/bazelisk coverage --combined_report=lcov //cli/... //tools:coverage_check_test --enable_bzlmod=true --enable_workspace=false
      - name: Regenerate coverage badge
        env:
          USE_BAZEL_VERSION: '9.x'
          COVERAGE_THRESHOLD: '90'
        run: ~/go/bin/bazelisk run //tools:coverage-check -- --badge-json coverage.json bazel-out/_coverage/_coverage_report.dat
      - name: Open PR if coverage badge changed
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          if [ -z "$(git status --porcelain coverage.json)" ]; then
            echo "coverage.json unchanged; nothing to do."
            exit 0
          fi
          NEW_COVERAGE="$(python3 -c 'import json,sys; print(json.load(open("coverage.json"))["message"])')"
          BRANCH="ci/coverage-badge-update"
          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git checkout -B "$BRANCH"
          git add coverage.json
          git commit -m "ci: update coverage badge to ${NEW_COVERAGE}"
          # Force-push the dedicated, bot-owned branch so re-runs reuse one PR
          # instead of accumulating stale branches. This never touches master.
          git push --force origin "$BRANCH"
          if gh pr view "$BRANCH" --json state --jq '.state' 2>/dev/null | grep -q OPEN; then
            echo "PR already open for $BRANCH; it now points at the latest badge."
          else
            gh pr create \
              --base master \
              --head "$BRANCH" \
              --title "ci: update coverage badge to ${NEW_COVERAGE}" \
              --body "Automated coverage badge refresh. Main-source line coverage is now **${NEW_COVERAGE}**."
          fi