Vitest fast unit testing framework powered by Vite with Jest-compatible API. Use when writing tests, mocking, configuring coverage, or working with test filtering and fixtures.
Vitest is a next-generation testing framework powered by Vite. It provides a Jest-compatible API with native ESM, TypeScript, and JSX support out of the box. Vitest shares the same config, transformers, resolvers, and plugins with your Vite app.
Key Features:
Vite-native: Uses Vite's transformation pipeline for fast HMR-like test updates
Jest-compatible: Drop-in replacement for most Jest test suites
Smart watch mode: Only reruns affected tests based on module graph
Native ESM, TypeScript, JSX support without configuration
Multi-threaded workers for parallel test execution
Built-in coverage via V8 or Istanbul
Snapshot testing, mocking, and spy utilities
The skill is based on Vitest 3.x, generated at 2026-01-28.
Core
Topic
Description
Reference
Configuration
Vitest and Vite config integration, defineConfig usage