What is Testing?

Testing ensures your application works correctly and continues to work as you make changes. This includes unit tests for individual functions, integration tests for component interactions, and end-to-end tests for complete user flows.

Why is it Important?

Tests catch bugs before users do, enable confident refactoring, and serve as documentation. Companies with mature engineering practices require testing skills. Test-driven development (TDD) is valued in many teams.

What to Learn

• Testing fundamentals (unit, integration, e2e)
• Jest and Vitest
• React Testing Library
• Cypress or Playwright for e2e
• Mocking and test doubles
• Test-driven development

Career Relevance

Testing skills are increasingly required, especially for senior roles. Companies value developers who write testable code and contribute to test suites. Many interviews include testing questions.