mutation.yaml

name: Mutation Testing

on:
  pull_request:
  schedule:
    - cron: "0 2 * * *"
  workflow_dispatch:

permissions:
  contents: read

concurrency:
  group: mutation-${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
  cancel-in-progress: true

env:
  GO_VERSION: "1.26"
  RAGCLI_MUTATION: "1"
  MUTATION_ARTIFACT_DIR: .artifacts/mutation
  MUTATION_OUTPUT: .artifacts/mutation/mutation-report.json

jobs:
  mutation:
    name: Gremlins
    runs-on: ubuntu-latest

    steps:
      - name: Checkout
        uses: actions/checkout@v5
        with:
          fetch-depth: 0

      - name: Setup Go
        uses: actions/setup-go@v6
        with:
          go-version: ${{ env.GO_VERSION }}
          cache: true

      - name: Prepare mutation artifacts
        run: mkdir -p "${MUTATION_ARTIFACT_DIR}"

      - name: Run Gremlins on PR diff
        id: gremlins_pr
        if: github.event_name == 'pull_request'
        continue-on-error: true
        uses: go-gremlins/gremlins-action@v1
        with:
          version: v0.6.0
          args: --output "${{ env.MUTATION_OUTPUT }}" --output-statuses lctv --diff "origin/${{ github.base_ref }}"

      - name: Run Gremlins on full repository
        id: gremlins_full
        if: github.event_name != 'pull_request'
        continue-on-error: true
        uses: go-gremlins/gremlins-action@v1
        with:
          version: v0.6.0
          args: --output "${{ env.MUTATION_OUTPUT }}" --output-statuses lctv

      - name: Upload mutation report
        if: always()
        uses: actions/upload-artifact@v4
        with:
          name: mutation-report
          path: ${{ env.MUTATION_ARTIFACT_DIR }}
          if-no-files-found: ignore

      - name: Write mutation summary
        if: always()
        env:
          MUTATION_OUTPUT: ${{ env.MUTATION_OUTPUT }}
        run: |
          python3 - <<'PY'
          import json
          import os
          from pathlib import Path

          summary_path = os.environ["GITHUB_STEP_SUMMARY"]
          report_path = Path(os.environ["MUTATION_OUTPUT"])

          lines = ["## Mutation Testing", ""]
          if not report_path.exists():
              lines.append("Mutation report was not produced.")
          else:
              report = json.loads(report_path.read_text(encoding="utf-8"))
              lines.extend([
                  f"- Test efficacy: {report.get('test_efficacy', 0):.2f}%",
                  f"- Mutations coverage: {report.get('mutations_coverage', 0):.2f}%",
                  f"- Mutants total: {report.get('mutants_total', 0)}",
                  f"- Killed: {report.get('mutants_killed', 0)}",
                  f"- Lived: {report.get('mutants_lived', 0)}",
                  f"- Not covered: {report.get('mutants_not_covered', 0)}",
                  f"- Not viable: {report.get('mutants_not_viable', 0)}",
                  f"- Elapsed time: {report.get('elapsed_time', 0):.3f}s",
              ])

          with open(summary_path, "a", encoding="utf-8") as fh:
              fh.write("\n".join(lines) + "\n")
          PY

      - name: Enforce mutation thresholds
        if: always()
        run: |
          if [[ "${{ steps.gremlins_pr.outcome }}" == "failure" || "${{ steps.gremlins_full.outcome }}" == "failure" ]]; then
            echo "Gremlins mutation thresholds were not met." >&2
            exit 1
          fi