Last Updated: November 21, 2025
Vitest
Fast Vite-native unit testing
Core Features
| Item | Description |
|---|---|
Vite Integration
|
Native Vite support |
Jest Compatible
|
Similar API to Jest |
Fast
|
Powered by Vite and esbuild |
ESM First
|
ES modules by default |
TypeScript
|
Built-in TypeScript |
Watch Mode
|
Fast HMR-like reruns |
Basic Test
import { describe, it, expect, beforeEach } from 'vitest'
describe('Math operations', () => {
it('should add numbers', () => {
expect(1 + 1).toBe(2)
})
it('should multiply', () => {
expect(2 * 3).toBe(6)
})
})
// Async tests
it('fetches data', async () => {
const data = await fetchUser(1)
expect(data.name).toBe('John')
})
// Mock
import { vi } from 'vitest'
const mockFn = vi.fn()
mockFn('hello')
expect(mockFn).toHaveBeenCalledWith('hello')Common Commands
npm install -D vitest
Install Vitest
vitest
Run tests in watch mode
vitest run
Run tests once
vitest --coverage
Generate coverage report
vitest --ui
Open web UI
Best Practices
- Use describe blocks to organize tests
- Mock external dependencies
- Use beforeEach for setup
- Keep tests focused and isolated
💡 Pro Tips
Quick Reference
Vitest is 10x faster than Jest for Vite projects