𝗧𝗲𝘀𝘁𝗶𝗻𝗴 𝗮𝗻𝗱 𝗗𝗲𝗯𝘂𝗴𝗴𝗶𝗻𝗴 𝗥𝗲𝗮𝗰𝘁 𝗔𝗽𝗽𝘀
Stop guessing if your code works. Use testing to build confidence.
Most developers skip testing because they find the setup too hard. They treat testing as a chore instead of a safety net.
You do not write tests for a computer. You write tests for your future self. When you change a function at 2 AM, tests tell you immediately if you broke something.
Think of testing as a pyramid:
• Unit Tests: Test one function or component. These are fast and numerous. • Integration Tests: Test how parts work together. These give you high confidence. • E2E Tests: Test the full app in a browser. Use these only for critical paths like login or checkout.
The golden rule of React Testing Library: Test what the user sees.
Do not test state variables. Do not test CSS classes. Do not test internal logic. Test the buttons, the text, and the inputs. If a user cannot see it, do not test it.
Follow the Arrange, Act, Assert pattern:
- Arrange: Render your component.
- Act: Click a button or type in a field.
- Assert: Check if the correct text appears on the screen.
For async code like API calls, use waitFor. This allows your test to wait for the data to load before checking the result.
If your app crashes in production, use Error Boundaries. They prevent one broken component from turning your entire page into a white screen. They provide a graceful fallback for your users.
Quick debugging checklist:
- Check the browser console for errors.
- Check the Network tab to see API responses.
- Use React DevTools to inspect props and state.
- Check if you are mutating state directly.
- Verify your useEffect dependency arrays.
Focus on testing what matters. You do not need 100% coverage. You need to cover the features that would hurt if they failed.
Source: https://dev.to/kushang_tailor/testing-debugging-react-apps-write-code-you-can-actually-trust-5334