coverage-enforce - SKILL.md Agent Skill

name: coverage-enforce description: "Enforce test coverage thresholds — configure Istanbul/c8, set targets, integrate with CI, identify gaps, and create tasks for uncovered code. Triggers: coverage, test coverage, coverage report, coverage threshold, untested code"

Coverage Enforce

Configure and enforce test coverage thresholds across the project.

Tech Stack

Vitest + c8 (v8 provider) | Jest + Istanbul | lcov + html reports

Playbook

1. Configure the coverage tool

Vitest — add to vite.config.ts:

test: {
  coverage: {
    provider: 'v8',
    reporter: ['text', 'lcov', 'html'],
    include: ['src/**/*.ts'],
    exclude: ['src/**/*.test.ts', 'src/**/*.d.ts'],
  },
}

Jest — add to jest.config.ts:

collectCoverage: true,
coverageReporters: ['text', 'lcov', 'html'],
collectCoverageFrom: ['src/**/*.ts', '!src/**/*.test.ts'],

2. Set coverage thresholds

thresholds: { statements: 80, branches: 75, functions: 80, lines: 80 }

Critical modules (auth, payments): raise to 90%.

3. Add to CI pipeline

- name: Run tests with coverage
  run: npm run test:coverage

Fail the pipeline if coverage drops below thresholds.
Optionally post coverage summary as a PR comment.

4. Identify uncovered code

Open coverage/index.html for interactive report.
Sort by lowest coverage; flag files at 0%.
Look for untested branches (if/else, switch, ternary).

5. Create test tasks for gaps

For each uncovered module: file path, current %, missing branches.
Prioritize critical modules first.
Track in project backlog or state/STATE.md.

6. Prevent coverage regression

Use --changedSince=main (Jest) for local fast checks.
Block merges if coverage on new code is below 90%.