TypeScript Testing

Core testing patterns for TypeScript and JavaScript projects using Vitest, Testing Library, MSW, and Playwright.

When to Activate

• Setting up a test suite for a TypeScript/JavaScript project
• Writing unit, integration, or component tests
• Configuring Vitest, Jest, or Playwright
• Mocking APIs with MSW
• Achieving 80%+ code coverage
• Migrating from Jest to Vitest on an ESM or Vite-based project
• Debugging tests that share mock state across runs and fail non-deterministically
• Setting up React Testing Library with userEvent for realistic component interaction testing

Framework Selection