Vitest

A comprehensive guide for implementing JavaScript and TypeScript testing strategies. Covers unit testing, integration testing, mocking patterns, React component testing with Testing Library, test fixtures, and best practices for test-driven development using Jest and Vitest.

This skill provides comprehensive guidance for JavaScript and TypeScript development, covering testing frameworks (Jest, Vitest, Testing Library), modern ES6+ patterns including async/await and functional programming, Node.js backend architecture with Express/Fastify, and advanced TypeScript type system features like generics and conditional types.