django/.github/workflows/coverage_comment.yml

name: Coverage Comment

on:
  workflow_run:
    workflows: ["Coverage Tests"]
    types:
      - completed

permissions:
  contents: read
  actions: read
  pull-requests: write

jobs:
  comment:
    if: >
      github.event.workflow_run.event == 'pull_request' &&
      github.event.workflow_run.conclusion == 'success' &&
      github.repository == 'django/django'
    name: Post Coverage Comment
    runs-on: ubuntu-latest
    timeout-minutes: 60
    steps:
      - name: Download coverage artifacts
        uses: actions/download-artifact@v4
        with:
          name: coverage-artifacts
          github-token: ${{ secrets.GITHUB_TOKEN }}
          run-id: ${{ github.event.workflow_run.id }}

      - name: Read PR number
        id: pr
        run: |
          pr_number=$(cat pr_number.txt)
          echo "number=$pr_number" >> $GITHUB_OUTPUT

      - name: Post/update PR comment
        env:
          PR_NUMBER: ${{ steps.pr.outputs.number }}
        uses: actions/github-script@v8
        with:
          script: |
            const fs = require('fs');
            const reportPath = 'diff-cover-report.md';
            let body = 'No coverage data available.';
            if (fs.existsSync(reportPath)) {
              body = fs.readFileSync(reportPath, 'utf8');
            }
            const commentBody = '### 📊 Coverage Report for Changed Files\n\n```\n' + body + '\n```\n\n**Note:** Missing lines are warnings only. Some lines may not be covered by SQLite tests as they are database-specific.\n\nFor more information about code coverage on pull requests, see the [contributing documentation](https://docs.djangoproject.com/en/dev/internals/contributing/writing-code/unit-tests/#code-coverage-on-pull-requests).';

            const prNumber = parseInt(process.env.PR_NUMBER);
            if (isNaN(prNumber)) {
              core.setFailed('PR number is not available or invalid.');
              return;
            }
            
            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: prNumber,
            });
            
            for (const c of comments) {
              if ((c.body || '').includes('📊 Coverage Report for Changed Files')) {
                await github.rest.issues.deleteComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  comment_id: c.id,
                });
              }
            }

            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: prNumber,
              body: commentBody,
            });