What it does. 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
Highlights
- 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
When to use it. 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.
Install
npx skills add antfu/skills --skill vitest
Or copy the skill folder manually:
git clone https://github.com/antfu/skills.git
cp -r skills/skills/vitest/ ~/.claude/skills/vitest
Source: antfu/skills — 5,833 stars, MIT, last pushed 2026-06-23.
