Jest / Testing Library
The standard JavaScript testing stack — Jest as the test runner and assertion library, Testing Library for component testing that mirrors user behavior.
Jest is the dominant JavaScript test runner, widely used for unit and integration testing across both frontend and Node.js backends. React Testing Library (part of the Testing Library family) encourages testing components the way users interact with them rather than testing implementation details. Together they form the baseline testing stack expected at most professional engineering teams. Vitest is an emerging alternative built for Vite projects.
Typical time to job-readiness: ~3 weeks.