# Test Coverage

> Analyze coverage, prioritize untested risk hotspots, generate missing tests, and verify threshold improvements.

- Skill: `materialofair/test-coverage-2` (Agent Skill)
- Install (CLI): `npx skillmds@latest add materialofair/test-coverage-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/materialofair/test-coverage-2/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: materialofair (https://skillmd.com/u/materialofair)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/materialofair/test-coverage-2

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# Test Coverage

Use this skill to close meaningful coverage gaps, not just raise percentages.

## Workflow

1. Run coverage:
   - `pnpm test --coverage` or `npx vitest run --coverage`
2. Parse summary and rank low-coverage files by risk:
   - Business-critical logic
   - Error handling paths
   - Security-sensitive branches
3. Generate targeted tests:
   - Unit for pure functions
   - Integration for service/API boundaries
   - E2E for critical user journeys
4. Re-run coverage and report before/after delta.

## Coverage Rules

- Use thresholds per project policy; default target can start at 80%.
- Cover meaningful branches and failure modes, not only statements.
- Exclude generated/build/vendor files explicitly.
- Enable all-file analysis when feasible to avoid hidden zero-coverage files.

## Vitest Guidance

- Default provider is V8; use Istanbul if project requires instrumentation parity.
- Configure `coverage.include`, `coverage.exclude`, and `coverage.thresholds`.

## References

- Vitest coverage guide: https://vitest.dev/guide/coverage.html
- Vitest coverage config: https://vitest.dev/config/#coverage