render function#

function render(
  component: React.Element<any>,
  options?: RenderOptions
): RenderResult

The render function is the entry point for writing React Native Testing Library tests. It deeply renders the given React element and returns helpers to query the output components' structure.

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

test('basic test', () => {
  render(<MyApp />);
  expect(screen.getAllByRole('button', { name: 'start' })).toBeOnTheScreen();
});

When using React context providers, like Redux Provider, you'll likely want to wrap rendered component with them. In such cases, it's convenient to create your own custom render method. Follow this great guide on how to set this up.

Options#

The behavior of the render method can be customized by passing various options as a second argument of the RenderOptions type:

wrapper option#

wrapper?: React.ComponentType<any>,

This option allows you to wrap the tested component, passed as the first option to the render() function, in an additional wrapper component. This is useful for creating reusable custom render functions for common React Context providers.

concurrentRoot option#

Set to true to enable concurrent rendering used in the React Native New Architecture. Otherwise render will default to legacy synchronous rendering.

createNodeMock option#

createNodeMock?: (element: React.Element) => unknown,

This option allows you to pass createNodeMock option to ReactTestRenderer.create() method in order to allow for custom mock refs. You can learn more about this option from React Test Renderer documentation.

unstable_validateStringsRenderedWithinText option#

unstable_validateStringsRenderedWithinText?: boolean;

This experimental option allows you to replicate React Native behavior of throwing Invariant Violation: Text strings must be rendered within a <Text> component error when you try to render string value under components different than <Text>, e.g., under <View>.

React Test Renderer does not enforce this check; hence, by default, React Native Testing Library also does not check this. That might result in runtime errors when running your code on a device, while the code works without errors in tests.

Result#

The render function returns the same queries and utilities as the screen object. We recommended using the screen object as more developer-friendly way.

See this article from Kent C. Dodds for more details.