Vitest testing framework patterns for test setup, async testing, mocking with vi.*, snapshots, and test performance (formerly test-vitest). This skill should be used when writing or debugging Vitest tests. This skill does NOT cover TDD methodology (use test-tdd skill), API mocking with MSW (use test-msw skill), or Jest-specific APIs.
Instalación
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Vitest testing framework patterns for test setup, async testing, mocking with vi.*, snapshots, and test performance (formerly test-vitest). This skill should be used when writing or debugging Vitest tests. This skill does NOT cover TDD methodology (use test-tdd skill), API mocking with MSW (use test-msw skill), or Jest-specific APIs.
Vitest Best Practices
Comprehensive performance optimization and best practices guide for Vitest testing framework. Contains 44 rules across 8 categories, prioritized by impact to guide test writing, refactoring, and code review.
When to Apply
Reference these guidelines when:
Writing new Vitest tests
Debugging flaky or slow tests
Setting up test configuration
Reviewing test code in PRs
Migrating from Jest to Vitest
Optimizing CI/CD test performance
Rule Categories by Priority
Priority
Category
Impact
Prefix
1
Async Patterns
CRITICAL
async-
2
Test Setup & Isolation
CRITICAL
setup-
3
Mocking Patterns
HIGH
mock-
4
Performance
HIGH
perf-
5
Snapshot Testing
MEDIUM
snap-
6
Environment
MEDIUM
env-
7
Assertions
LOW-MEDIUM
assert-
8
Test Organization
LOW
org-
Quick Reference
1. Async Patterns (CRITICAL)
async-await-assertions - Await async assertions to prevent false positives
async-return-promises - Return promises from test functions
async-fake-timers - Use fake timers for time-dependent code
async-waitfor-polling - Use vi.waitFor for async conditions
async-concurrent-expect - Use test context expect in concurrent tests
async-act-wrapper - Await user events to avoid act warnings
async-error-handling - Test async error handling properly
2. Test Setup & Isolation (CRITICAL)
setup-beforeeach-cleanup - Clean up state in afterEach hooks
setup-restore-mocks - Restore mocks after each test
setup-avoid-shared-state - Avoid shared mutable state between tests
setup-beforeall-expensive - Use beforeAll for expensive one-time setup
setup-reset-modules - Reset modules when testing module state
setup-test-factories - Use test factories for complex test data
