React Native Testing Library

React Native Testing Library, published as @testing-library/react-native and often shortened to RNTL, is a library for testing React Native components inside Jest. It renders a component, lets you find elements the way a user would, and lets you fire events like presses and typing.

Its guiding principle comes from the wider Testing Library family: the more your tests resemble the way your software is used, the more confidence they give. So instead of reaching into component state or props, you query what is on screen:

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

test('shows a greeting after sign in', () => {
  render(<SignIn />);
  fireEvent.changeText(screen.getByLabelText('Email'), 'ada@example.com');
  fireEvent.press(screen.getByRole('button', { name: 'Sign in' }));
  expect(screen.getByText('Welcome, Ada')).toBeOnTheScreen();
});

Prefer queries in roughly this order: by role, by label, by text, and only then by testID. Querying by role and label has a useful side effect: if a test cannot find your button by its role, a screen reader probably cannot either.

Common gotchas:

• getBy versus findBy. getBy* looks synchronously; findBy* waits, and is what you need after a fetch or any async state update.
• Act warnings. Updates that happen after the test finishes trigger warnings about act. Await the UI change you expect instead of ignoring them.
• It is not a device. RNTL renders in Node.js, so layout, styles and native behaviour are not real. It verifies behaviour and content, not appearance.

RNTL is maintained by Callstack and has become the standard way to write component tests in React Native.