mutation.yml

# Scheduled mutation-testing run.
#
# The shared CI gate runs the pass/fail unit suite, not Stryker: a mutation run
# is too slow to sit on every push, so it needs its own cadence rather than
# riding on push or pull_request. thresholds.break is null in the Stryker
# config, so a low score never fails this job; the artifact is what a human
# reads to judge whether coverage of src/XChainDecoder/** moved.
name: mutation

# Least privilege for the default GITHUB_TOKEN: every job here only reads the
# repo; uploading the report artifact needs no elevated scope.
permissions:
  contents: read

on:
  schedule:
    # Sundays 09:00 UTC. Mutation runs are heavy; weekly keeps the cadence
    # cheap while still catching drift within a week of it landing.
    - cron: "0 9 * * 0"
  # Re-run on demand, e.g. right after a change to src/XChainDecoder/**.
  workflow_dispatch:

jobs:
  mutation:
    runs-on: ubuntu-latest
    timeout-minutes: 90
    steps:
      - uses: actions/checkout@v4

      - name: Use Node.js 22
        uses: actions/setup-node@v4
        with:
          node-version: "22"
          cache: npm

      - name: Install dependencies
        run: npm ci

      - name: Run Stryker mutation testing
        run: npm run test:mutation

      # The html reporter always writes reports/mutation/index.html on a
      # completed run; fail loudly here rather than let upload-artifact
      # silently skip an empty directory, which would look green forever.
      - name: Verify the report is nonempty
        run: |
          set -euo pipefail
          if [ ! -s reports/mutation/index.html ]; then
            echo "::error::reports/mutation/index.html is missing or empty"
            exit 1
          fi

      - name: Archive mutation report
        if: always()
        uses: actions/upload-artifact@v4
        with:
          name: mutation-report
          path: reports/mutation/
          retention-days: 30