Tests Are an Investment, Not an Expense
Many developers put off writing tests for later, but that later never comes. Tests save time, especially in the long run.
Unit Tests: The Foundation of Confidence
Unit tests verify individual functions in isolation. For JavaScript, we use Vitest. Every function with business logic should have unit tests.
Integration Tests: Checking Interactions
For React components, we use Testing Library. It forces you to test behavior, not implementation.
E2E Tests: Verifying User Scenarios
For E2E, we use Playwright. E2E tests are the slowest, so there should be the fewest of them. Test only critical scenarios.
The Test Pyramid
Ideal ratio: many unit tests (70%), moderate integration tests (20%), few E2E tests (10%).
CI Integration
Tests without CI are just files on disk. Set up GitHub Actions for automatic execution.
Conclusion
Do not try to cover everything at once — start with the most critical business functions. Tests are an investment in peace of mind.