Testing React Applications

Testing pyramid

• Unit tests: pure functions and small components
• Integration tests: component behavior with dependencies
• End-to-end tests: critical user journeys

Recommended tools

• Vitest or Jest
• React Testing Library
• Playwright or Cypress

Component test example

import { render, screen, fireEvent } from '@testing-library/react';

render(<Counter />);
fireEvent.click(screen.getByRole('button', { name: /increment/i }));
expect(screen.getByText('1')).toBeInTheDocument();

Testing best practices

• Test behavior, not implementation details
• Prefer accessible queries (getByRole)
• Cover critical business flows first

Next, we will handle runtime UI failures with error boundaries.