coverage.yml

name: coverage

# measures the test coverage (npm run coverage) of every pushed branch and pull requests from forks, and how it
# changed: compared with the commit before the push on master, else with where the branch (or pull request) left
# master, measured in the same job. The job summary shows it; pushes to master get it as a commit comment, pushes to a
# branch with a pull request as a comment on it (one, updated by later pushes). Pull requests from forks have no
# write access: only the job summary
on:
  push:
    branches: ['**']
  pull_request:

concurrency:
  group: coverage-${{ github.event_name }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  coverage:
    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.repository
    runs-on: ubuntu-latest
    permissions:
      contents: write
      pull-requests: write
    steps:
    - uses: actions/checkout@v7
      with:
        fetch-depth: 0
    - uses: actions/setup-node@v7
      with:
        node-version: 24.x

    - run: npm install
    - run: npm run coverage

    # the base, measured in a second checkout: skipped without one (a new branch, a force push that dropped it, a
    # base from before npm run coverage existed), and a base whose tests fail just gives no comparison
    - id: base
      continue-on-error: true
      run: |
        if [ "$EVENT" = pull_request ]; then base=$(git merge-base "$PR_BASE" HEAD); name="the pull request's base"
        elif [ "$REF" = refs/heads/master ]; then base=$BEFORE; name="the previous commit on master"
        else base=$(git merge-base origin/master HEAD); name="master where the branch left it"; fi
        if [ -z "$base" ] || ! git cat-file -e "$base^{commit}" 2>/dev/null || [ "$base" = "$(git rev-parse HEAD)" ]; then
          echo "no base to compare with"; exit 0
        fi
        git worktree add -q ../base "$base"
        cd ../base
        if ! node -e "process.exit(require('./package.json').scripts?.coverage ? 0 : 1)"; then echo "the base has no npm run coverage"; exit 0; fi
        npm install && npm run coverage
        echo "summary=$PWD/coverage/coverage-summary.json" >> "$GITHUB_OUTPUT"
        echo "root=$PWD" >> "$GITHUB_OUTPUT"
        echo "name=$name (${base:0:7})" >> "$GITHUB_OUTPUT"
      env:
        EVENT: ${{ github.event_name }}
        REF: ${{ github.ref }}
        BEFORE: ${{ github.event.before }}
        PR_BASE: ${{ github.event.pull_request.base.sha }}
    - if: steps.base.outputs.summary
      run: node scripts/coverage-report.js "$SUMMARY" "$ROOT"
      env:
        SUMMARY: ${{ steps.base.outputs.summary }}
        ROOT: ${{ steps.base.outputs.root }}
        BASE_NAME: ${{ steps.base.outputs.name }}
    - run: cat coverage/report.md >> "$GITHUB_STEP_SUMMARY"

    - if: github.event_name == 'push' && github.ref == 'refs/heads/master'
      run: gh api "repos/$REPOSITORY/commits/$SHA/comments" -F body=@coverage/report.md
      env:
        GH_TOKEN: ${{ github.token }}
        REPOSITORY: ${{ github.repository }}
        SHA: ${{ github.sha }}

    # the pull request of the pushed branch, if any: its coverage comment is updated, or posted the first time
    - if: github.event_name == 'push' && github.ref != 'refs/heads/master'
      run: |
        pr=$(gh pr list --head "$BRANCH" --state open --json number --jq '.[0].number')
        if [ -z "$pr" ]; then echo "no pull request"; exit 0; fi
        comment=$(gh api "repos/$REPOSITORY/issues/$pr/comments" --paginate --jq '.[] | select(.body | startswith("<!-- coverage -->")) | .id' | head -1)
        if [ -n "$comment" ]; then gh api -X PATCH "repos/$REPOSITORY/issues/comments/$comment" -F body=@coverage/report.md
        else gh api "repos/$REPOSITORY/issues/$pr/comments" -F body=@coverage/report.md; fi
      env:
        GH_TOKEN: ${{ github.token }}
        REPOSITORY: ${{ github.repository }}
        BRANCH: ${{ github.ref_name }}