Custom Fixtures with test.extend in Vitest
From the Vitest cheat sheet · Test Context & Fixtures · verified Nov 2026
Custom Fixtures with test.extend
Create reusable setup with automatic cleanup and inferred types
typescript
// my-test.ts
import { test as base } from 'vitest'
export const test = base
.extend('baseUrl', 'http://localhost:3000')
.extend('api', ({ baseUrl }) => createClient(baseUrl))
// users.test.ts
test('lists users', async ({ api }) => {
expect(await api.get('/users')).toHaveLength(2)
})📌 The builder API (4.1+) infers fixture types from return values
💡 Fixtures are lazy: only the ones a test destructures are created
⚠️ A file or worker fixture can't depend on a test-scoped one
🔍 onCleanup works once per fixture; split fixtures for more cleanup
fixturestest.extendonCleanup
Continue with Vitest
Save the full cheat sheet or work through every related task.