Testing & Debugging

Testing and debugging are critical to ensuring your frontend applications are reliable and maintainable. This guide covers key techniques and tools for both.

Unit Testing

Definition: Testing individual components or functions to verify they work as expected.
Tools:
- Jest: A popular JavaScript testing framework.
- Mocha: A flexible testing framework for Node.js.
Example using Jest:

// sum.js
export function sum(a, b) {
  return a + b;
}
 
// sum.test.js
import { sum } from './sum';
 
test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});

Integration & End-to-End Testing

Integration Testing: Verifies that multiple parts of your application work together.
- React Testing Library: Helps test React components in a way that mimics user interactions.
End-to-End Testing: Simulates real user scenarios.
- Cypress: A powerful tool for writing end-to-end tests.

Debugging Techniques

Browser Developer Tools: Use Chrome DevTools, Firefox Developer Tools, etc., to inspect elements, debug JavaScript, and analyze performance.
Console Logging: Utilize console.log, console.error, etc., to trace code execution.
Source Maps: Enable source maps to debug transpiled or minified code.
Error Boundaries (in React): Catch JavaScript errors in components and display fallback UIs.

Best Practices

Write tests concurrently with your code.
Automate tests in your CI/CD pipeline.
Regularly update tests to reflect code changes.

Additional Resources

📊 State Management ♿ Accessibility