React Testing Library And Jest- The Complete Guide Apr 2026

test('should increment counter', () => const result = renderHook(() => useCounter(0))

const button = screen.getByRole('button') expect(button).toHaveTextContent('OFF')

if (!user) return <div>Loading...</div> return <div>user.name</div> React Testing Library and Jest- The Complete Guide

import userEvent from '@testing-library/user-event' test('form submission', async () => const user = userEvent.setup() render(<LoginForm />)

expect(screen.getByText('Loading...')).toBeInTheDocument() test('should increment counter', () =&gt; const result =

jest.useRealTimers() // restore Controlled component const Toggle = () => const [on, setOn] = useState(false) return ( <button onClick=() => setOn(!on)> on ? 'ON' : 'OFF' </button> )

await user.click(button) expect(button).toHaveTextContent('ON') test('should increment counter'

// Don't use act directly (userEvent handles it) act(() => render(<Component />) )

act(() => jest.advanceTimersByTime(1000) )