cli-testing-specialist 1.0.10

name: Mutation Testing

on:
  # Run on push to main branch
  push:
    branches: [main]
  # Run on pull requests
  pull_request:
    branches: [main]
  # Allow manual trigger
  workflow_dispatch:
  # Weekly schedule (Sundays at 00:00 UTC)
  schedule:
    - cron: '0 0 * * 0'

env:
  CARGO_TERM_COLOR: always
  RUST_BACKTRACE: 1

jobs:
  mutation-testing:
    name: Mutation Testing
    runs-on: ubuntu-latest
    timeout-minutes: 60

    steps:
      - name: Checkout code
        uses: actions/checkout@v4

      - name: Install Rust toolchain
        uses: dtolnay/rust-toolchain@stable
        with:
          components: rustfmt, clippy

      - name: Cache Rust dependencies
        uses: Swatinem/rust-cache@v2
        with:
          cache-on-failure: true

      - name: Install cargo-mutants
        run: cargo install cargo-mutants --locked
        env:
          CARGO_INSTALL_OPTS: --force

      - name: Run baseline tests
        run: cargo test --lib --all-features
        continue-on-error: false

      - name: Run mutation testing
        id: mutants
        run: |
          cargo mutants --all-features --output mutants-out 2>&1 | tee mutation-test.log
        continue-on-error: true

      - name: Parse mutation testing results
        id: results
        run: |
          # Extract mutation score from output
          if [ -f mutants-out/mutants.out ]; then
            MUTATION_SCORE=$(grep -oP 'caught \K[0-9]+\.[0-9]+%' mutants-out/mutants.out | tail -1 || echo "0.0%")
            CAUGHT=$(grep -oP 'caught: \K[0-9]+' mutants-out/mutants.out | tail -1 || echo "0")
            MISSED=$(grep -oP 'missed: \K[0-9]+' mutants-out/mutants.out | tail -1 || echo "0")
            TIMEOUT=$(grep -oP 'timeout: \K[0-9]+' mutants-out/mutants.out | tail -1 || echo "0")
            TOTAL=$(grep -oP 'total: \K[0-9]+' mutants-out/mutants.out | tail -1 || echo "0")
          else
            MUTATION_SCORE="N/A"
            CAUGHT="0"
            MISSED="0"
            TIMEOUT="0"
            TOTAL="0"
          fi

          echo "mutation_score=$MUTATION_SCORE" >> $GITHUB_OUTPUT
          echo "caught=$CAUGHT" >> $GITHUB_OUTPUT
          echo "missed=$MISSED" >> $GITHUB_OUTPUT
          echo "timeout=$TIMEOUT" >> $GITHUB_OUTPUT
          echo "total=$TOTAL" >> $GITHUB_OUTPUT

      - name: Upload mutation testing artifacts
        uses: actions/upload-artifact@v4
        if: always()
        with:
          name: mutation-testing-results
          path: |
            mutants-out/
            mutation-test.log
          retention-days: 30

      - name: Comment PR with mutation score
        if: github.event_name == 'pull_request'
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const mutation_score = '${{ steps.results.outputs.mutation_score }}';
            const caught = '${{ steps.results.outputs.caught }}';
            const missed = '${{ steps.results.outputs.missed }}';
            const timeout = '${{ steps.results.outputs.timeout }}';
            const total = '${{ steps.results.outputs.total }}';

            const comment = `## 🧬 Mutation Testing Results

            | Metric | Value |
            |--------|-------|
            | **Mutation Score** | ${mutation_score} |
            | Caught | ${caught} |
            | Missed | ${missed} |
            | Timeout | ${timeout} |
            | **Total Mutants** | ${total} |

            ${missed > 0 ? '⚠️ **Warning**: Some mutants were missed. Consider adding more tests to improve coverage.' : '✅ **Excellent**: All mutants were caught!'}

            <details>
            <summary>📊 View detailed results</summary>

            Download the full mutation testing report from the workflow artifacts.

            **What is Mutation Testing?**
            Mutation testing evaluates test quality by introducing intentional bugs (mutations) and checking if tests catch them. A high mutation score indicates robust tests.

            **Interpretation**:
            - **Caught**: Tests detected the mutation (good)
            - **Missed**: Tests passed despite the mutation (needs improvement)
            - **Timeout**: Test took too long (possible infinite loop)

            </details>
            `;

            github.rest.issues.createComment({
              issue_number: context.issue.number,
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: comment
            });

      - name: Check mutation score threshold
        run: |
          SCORE=$(echo "${{ steps.results.outputs.mutation_score }}" | sed 's/%//')
          if [ "$SCORE" != "N/A" ] && [ "$(echo "$SCORE < 80" | bc -l)" -eq 1 ]; then
            echo "⚠️ Mutation score ($SCORE%) is below threshold (80%)"
            echo "::warning::Mutation score is below 80%. Consider improving test quality."
          else
            echo "✅ Mutation score ($SCORE%) meets or exceeds threshold (80%)"
          fi

      - name: Generate mutation testing badge
        if: github.ref == 'refs/heads/main'
        run: |
          SCORE="${{ steps.results.outputs.mutation_score }}"
          COLOR="red"
          if [ "$SCORE" != "N/A" ]; then
            SCORE_NUM=$(echo "$SCORE" | sed 's/%//')
            if [ "$(echo "$SCORE_NUM >= 80" | bc -l)" -eq 1 ]; then
              COLOR="brightgreen"
            elif [ "$(echo "$SCORE_NUM >= 60" | bc -l)" -eq 1 ]; then
              COLOR="yellow"
            fi
          fi

          echo "Mutation Score: $SCORE ($COLOR)"
          # Badge URL: https://img.shields.io/badge/mutation-${SCORE}-${COLOR}