vitest-best-practices

# Vitest Best Practices ## When to Apply This Skill Use this skill when you encounter any of these scenarios: ### File Patterns - Working with `*.test.ts`, `*.spec.ts`, or similar test files - Creating new test files for TypeScript/JavaScript modules - Reviewing existing vitest test suites ### User Intent Keywords - User mentions: vitest, testing, TDD, BDD, unit tests, integration tests - User asks to: write tests, add test coverage, fix failing tests, refactor tests - User discusses: mocking, stubbing, assertions, test performance, test organization ### Code Context - Files importing from `vitest` (`describe`, `it`, `expect`, `vi`) - Test setup/teardown code (`beforeEach`, `afterEach`, `beforeAll`, `afterAll`) - Mock/spy implementations using `vi.mock()`, `vi.spyOn()`, `vi.fn()` - Assertion chains (`expect(...).toEqual()`, `.toBe()`, `.toThrow()`, etc.) ### Common Tasks - Writing new test cases for existing functionality - Refactoring tests for better clarity or performance - Debugging flaky or failing tests - Improving test coverage or maintainability - Reviewing test code for best practices compliance ## Do NOT Use This Skill When - Writing end-to-end tests with Playwright/Cypress (different scope) - The task is purely about implementation code, not tests ## What This Skill Covers This skill provides comprehensive guidance on: 1. **Test Organization**: File placement, naming conventions, grouping strategies 2. **AAA Pattern**: Arrange, Act, Assert structure ...