renovate/.github/workflows/mutation.yml

name: Mutation Testing

on:
  schedule:
    - cron: '0 3 * * 0' # Weekly on Sundays at 3am
  workflow_dispatch:
  pull_request:
    types: [opened, synchronize]

permissions:
  contents: read

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

env:
  NODE_VERSION: 24

jobs:
  mutation-full:
    if: github.event_name == 'schedule' || github.event_name == 'workflow_dispatch'
    runs-on: ubuntu-latest
    continue-on-error: true
    steps:
      - name: Checkout code
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          persist-credentials: false
          show-progress: false

      - name: Setup Node.js
        uses: ./.github/actions/setup-node
        with:
          node-version: ${{ env.NODE_VERSION }}
          os: ${{ runner.os }}

      - run: pnpm test:mutation

      - name: Upload mutation report
        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
        if: always()
        with:
          name: mutation-report
          path: reports/mutation/

  mutation-pr:
    if: github.event_name == 'pull_request'
    runs-on: ubuntu-latest
    continue-on-error: true
    permissions:
      contents: read
      pull-requests: write
    steps:
      - name: Checkout code
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          fetch-depth: 0
          persist-credentials: false
          show-progress: false

      - name: Setup Node.js
        uses: ./.github/actions/setup-node
        with:
          node-version: ${{ env.NODE_VERSION }}
          os: ${{ runner.os }}

      - name: Get changed source files
        id: changed
        env:
          BASE_REF: ${{ github.base_ref }}
        run: |
          FILES=$(git diff --name-only "origin/$BASE_REF...HEAD" -- 'lib/**/*.ts' ':!lib/**/*.spec.ts' ':!lib/**/*.generated.ts' | tr '\n' ',')
          echo "files=$FILES" >> "$GITHUB_OUTPUT"
          echo "has_files=$( [ -n "$FILES" ] && echo true || echo false )" >> "$GITHUB_OUTPUT"

      - name: Run mutation tests on changed files
        if: steps.changed.outputs.has_files == 'true'
        env:
          CHANGED_FILES: ${{ steps.changed.outputs.files }}
        run: pnpm test:mutation:changed "$CHANGED_FILES"

      - name: Post PR comment
        if: always() && steps.changed.outputs.has_files == 'true'
        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
        with:
          script: |
            const fs = require('fs');
            let body = '## 🧬 Mutation Testing Results\n\n';
            try {
              const report = JSON.parse(fs.readFileSync('reports/mutation/mutation.json', 'utf8'));
              const score = report.schemaVersion ?
                (report.files ? Object.values(report.files).reduce((acc, f) => acc + f.mutationScore, 0) / Object.keys(report.files).length : 0) : 0;
              body += `**Mutation Score:** ${score.toFixed(1)}%\n\n`;
              body += '| File | Score | Survived | Killed | Total |\n|------|-------|----------|--------|-------|\n';
              for (const [file, data] of Object.entries(report.files || {})) {
                body += `| ${file} | ${data.mutationScore.toFixed(1)}% | ${data.survived || 0} | ${data.killed || 0} | ${data.totalMutants || 0} |\n`;
              }
            } catch (e) {
              body += '_No mutation report generated (possibly no mutants in changed files)._\n';
            }
            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner, repo: context.repo.repo, issue_number: context.issue.number
            });
            const existing = comments.find(c => c.body.includes('🧬 Mutation Testing Results'));
            if (existing) {
              await github.rest.issues.updateComment({ owner: context.repo.owner, repo: context.repo.repo, comment_id: existing.id, body });
            } else {
              await github.rest.issues.createComment({ owner: context.repo.owner, repo: context.repo.repo, issue_number: context.issue.number, body });
            }