callstack-react-native-testing-library

Developer-friendly and complete React Native testing utilities that encourage good testing practices.

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[!WARNING] Beta Version: This version (v14) is currently in beta. APIs and behavior may change before the stable release. Please report any issues you encounter.

For stable version (v13) see README-v13.md.

The problem

You want to write maintainable tests for your React Native components. Your tests should avoid implementation details and focus on giving you confidence. They should remain maintainable so refactors (changes to implementation but not functionality) don't break your tests and slow you and your team down.

This solution

The React Native Testing Library (RNTL) tests React Native components. It simulates the React Native runtime on top of Test Renderer and encourages better testing practices. Its primary guiding principle is:

The more your tests resemble the way your software is used, the more confidence they can give you.

This project is inspired by React Testing Library. Tested to work with Jest, but it should work with other test runners as well.

Installation

Open a Terminal in your project's folder and run:

npm install --save-dev @testing-library/react-native@alpha

This library has a peerDependencies listing for Test Renderer. Make sure to install it as a dev dependency:

npm install --save-dev test-renderer

Additional Jest matchers

You can use the built-in Jest matchers automatically by having any import from @testing-library/react-native in your test.

Example

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

test('form submits two answers', async () => {
  const questions = ['q1', 'q2'];
  const onSubmit = jest.fn();

  const user = userEvent.setup();
  await render(<QuestionsBoard questions={questions} onSubmit={onSubmit} />);

  const answerInputs = screen.getAllByLabelText('answer input');

  // simulates the user focusing on TextInput and typing text one char at a time
  await user.type(answerInputs[0], 'a1');
  await user.type(answerInputs[1], 'a2');

  // simulates the user pressing on any pressable element
  await user.press(screen.getByRole('button', { name: 'Submit' }));

  expect(onSubmit).toHaveBeenCalledWith({
    1: { q: 'q1', a: 'a1' },
    2: { q: 'q2', a: 'a2' },
  });
});

You can find the source of QuestionsBoard component and this example here.

API / Usage

React Native Testing Library consists of following APIs: