Vitest

If you're working with Vite-based projects or just tired of slow Jest startup times, this is the testing framework you want. Vitest gives you instant HMR-based test execution, native TypeScript support without configuration gymnastics, and a Jest-compatible API that makes migration straightforward. The skill covers the full testing stack: mocking with vi.mock and vi.spyOn, timer manipulation, type testing with expectTypeOf, and React Testing Library integration with proper jsdom setup. Coverage is handled by v8 instead of Istanbul, which is noticeably faster. The watch mode and optional UI are excellent for development workflow, and the examples show real patterns like beforeEach cleanup and mock implementation swapping that you'll actually use.

skills.sh installs: 942
GitHub stars: 79
last updated: Aug 21, 2026

View on GitHub

Install

$ npx -y skills add bobmatnyc/claude-mpm-skills --skill vitest --agent claude-code

Installs into .claude/skills of the current project.

Files

Vitest - Modern TypeScript Testing

Overview

Vitest is a next-generation test framework powered by Vite, designed for modern TypeScript/JavaScript projects. It provides blazing-fast test execution through HMR-based test running, native ESM support, and first-class TypeScript integration.

Key Features:

⚡ Vite-native: Instant HMR-based test execution (10-100x faster than Jest)
🎯 TypeScript-first: Built-in TypeScript support, no configuration needed
🔄 ESM-native: Native ES modules, async/await, top-level await
🧪 Jest-compatible: Compatible API for easy migration
📸 Snapshot testing: Built-in snapshot support
🎨 Component testing: React Testing Library, Vue Test Utils integration
📊 Coverage: Built-in v8/c8 coverage (faster than Istanbul)
🌐 UI mode: Beautiful web UI for test debugging

Installation:

npm install -D vitest
# TypeScript types (usually auto-detected)
npm install -D @vitest/ui  # Optional: UI mode

Basic Setup

1. Configure Vitest

vitest.config.ts:

import { defineConfig } from 'vitest/config';

SKILL.md on GitHub

Details

Repository: github.com/bobmatnyc/claude-mpm-skills
Categories: Testing & QA, Debugging, Design & UI/UX
First seen: May 16, 2026