coverage-comment.yml

---
name: Coverage Comment
on:  # yamllint disable-line rule:truthy  # zizmor: ignore[dangerous-triggers]
  workflow_run:
    workflows: [Test]
    types: [completed]
permissions:
  actions: read
  pull-requests: write
jobs:
  comment:
    runs-on: ubuntu-latest
    if: >-
      github.event.workflow_run.event == 'pull_request' &&
      github.event.workflow_run.conclusion == 'success'
    steps:
      - name: Download artifact
        # yamllint disable-line rule:line-length
        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093  # ratchet:actions/download-artifact@v4
        with:
          run-id: ${{ github.event.workflow_run.id }}
          name: pr
          github-token: ${{ secrets.GITHUB_TOKEN }}
      - name: Read PR number
        id: pr
        run: |
          pr_number=$(cat NR)
          if ! [[ "$pr_number" =~ ^[0-9]+$ ]]; then
            echo "Invalid PR number: $pr_number" >&2
            exit 1
          fi
          echo "number=$pr_number" >> "$GITHUB_OUTPUT"
      - name: Find baseline run
        id: baseline
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          python3 - <<'PYEOF'
          import json, os, urllib.request
          token = os.environ['GITHUB_TOKEN']
          repo = os.environ['GITHUB_REPOSITORY']
          url = (
              f'https://api.github.com/repos/{repo}/actions/workflows'
              f'/coverage-baseline.yml/runs'
              f'?branch=main&status=success&per_page=1'
          )
          req = urllib.request.Request(url, headers={
              'Authorization': f'Bearer {token}',
              'Accept': 'application/vnd.github+json',
          })
          with urllib.request.urlopen(req) as r:
              runs = json.loads(r.read()).get('workflow_runs', [])
          run_id = str(runs[0]['id']) if runs else ''
          with open(os.environ['GITHUB_OUTPUT'], 'a') as f:
              f.write(f'run-id={run_id}\n')
          PYEOF
      - name: Download baseline coverage
        if: steps.baseline.outputs.run-id != ''
        # yamllint disable-line rule:line-length
        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093  # ratchet:actions/download-artifact@v4
        with:
          run-id: ${{ steps.baseline.outputs.run-id }}
          name: main-coverage
          path: main/
          github-token: ${{ secrets.GITHUB_TOKEN }}
      - name: Compute coverage delta
        id: delta
        if: steps.baseline.outputs.run-id != ''
        run: |
          python3 - <<'PYEOF'
          import xml.etree.ElementTree as ET
          import os, sys
          try:
              pr_rate = ET.parse('coverage.xml').getroot().get('line-rate')
              main_xml = ET.parse('main/coverage.xml').getroot()
              main_rate = main_xml.get('line-rate')
              pr = float(pr_rate) * 100
              main = float(main_rate) * 100
              delta = pr - main
              if not (-100 <= delta <= 100):
                  raise ValueError(f"delta out of range: {delta}")
              sign = '+' if delta >= 0 else ''
              title = f"Coverage Report (Δ {sign}{delta:.1f}%)"
          except Exception as e:
              print(f"Warning: could not compute delta: {e}", file=sys.stderr)
              title = "Coverage Report"
          with open(os.environ['GITHUB_OUTPUT'], 'a') as f:
              f.write(f"title={title}\n")
          PYEOF
      - name: Post coverage comment
        # yamllint disable-line rule:line-length
        uses: MishaKav/pytest-coverage-comment@dd5b80bde6d16941f336518e92929e89069d8451  # ratchet:MishaKav/pytest-coverage-comment@v1.7.2
        with:
          pytest-xml-coverage-path: coverage.xml
          unique-id-for-comment: coverage
          issue-number: ${{ steps.pr.outputs.number }}
          title: ${{ steps.delta.outputs.title || 'Coverage Report' }}