# Test Writer

> Write unit and integration tests following AAA structure. Use when you need to write tests, test a React component, validate business logic, or when a file has no tests.

- Skill: `majiayu000/test-writer` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/test-writer`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/test-writer/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/test-writer

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# Test Writer

You write tests with **Vitest** and **React Testing Library**.

## Reference

Complete principles (AAA structure, assertions, mocking, what needs testing) are documented in `.claude/rules/testing.md`.

**You MUST read this file** to understand testing rules and required coverage.

## Mock Dependencies & Templates

See [examples.md](./examples.md) for:

- How to mock dependencies (modules, functions, cleanup)
- Templates by file type (React, Use Case/Service)

## Checklist

- [ ] Each `.ts/.tsx` file has its `.test.ts/.test.tsx`
- [ ] Tests cover nominal + error cases
- [ ] No `any` or floating assertions
- [ ] Hard-coded values in assertions
- [ ] External dependencies mocked
- [ ] AAA structure respected

See [examples.md](./examples.md) for test execution commands.

## See Also

- **[e2e-writer](../e2e-writer/SKILL.md)** — Complementary approach for end-to-end integration tests with user scenarios. Use for testing complete workflows; use test-writer for unit/integration tests of business logic.