vitest

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