React — Testing Library 'link'

// Or use waitFor for custom conditions await waitFor(() => { expect(screen.getByRole('alert')).toHaveTextContent('Success') }) // fireEvent - lower level, more immediate fireEvent.click(button) fireEvent.change(input, { target: { value: 'new' } }) // userEvent - higher level, more realistic (recommended) await userEvent.click(button) await userEvent.type(input, 'new text') await userEvent.selectOptions(select, 'option1') await userEvent.tab() // Focus management Testing Form Interactions test('submits form with user input', async () => { const handleSubmit = jest.fn() render(<LoginForm onSubmit={handleSubmit} />) // Fill form fields await userEvent.type(screen.getByLabelText(/email/i), 'test@example.com') await userEvent.type(screen.getByLabelText(/password/i), 'password123')

expect(handleSubmit).toHaveBeenCalledWith({ email: 'test@example.com', password: 'password123' }) }) import { renderHook, act } from '@testing-library/react' test('useCounter hook increments', () => { const { result } = renderHook(() => useCounter(0)) react testing library

// Wait for loading to complete expect(screen.getByText(/loading/i)).toBeInTheDocument() // Or use waitFor for custom conditions await