Jest setup for unit tests in React Native - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Jest in React Native testing?

Jest is a testing framework used to write and run unit tests for React Native apps. It helps check if components and functions work as expected.

beginner

Which command installs Jest and its React Native preset?

You run: npm install --save-dev jest @testing-library/react-native @testing-library/jest-native react-test-renderer to install Jest and tools for React Native testing.

intermediate

What is the purpose of jest.config.js in Jest setup?

The jest.config.js file tells Jest how to run tests, which files to look for, and how to handle React Native specifics.

intermediate

Why do we use react-test-renderer in React Native Jest tests?

It helps create a snapshot of a component’s UI so we can compare it later to catch unexpected changes.

beginner

How do you run Jest tests in a React Native project?

You run npm test or jest in the terminal to start Jest and run all tests.

What file usually contains Jest configuration in a React Native project?

A metro.config.js

B jest.config.js

C babel.config.js

D package.json

The jest.config.js file is the standard place to put Jest settings.

Which package helps to render React Native components for testing snapshots?

A react-native-snapshots

B jest-native

C react-test-renderer

D react-native-testing-library

react-test-renderer creates a serializable output of components for snapshot testing.

What command runs Jest tests in a React Native project?

A npm install

B npm run build

C npm start

D npm test

npm test runs the test script, which usually runs Jest.

Why do we mock native modules in Jest tests for React Native?

A To speed up tests and avoid errors from native code

B To make the app run faster on devices

C To add animations

D To improve UI design

Mocking native modules prevents errors and makes tests faster by simulating native behavior.

Which testing library is commonly used with Jest for React Native component testing?

A @testing-library/react-native

B Enzyme

C React Testing Library

D Mocha

@testing-library/react-native provides helpful tools to test React Native components with Jest.

Explain the steps to set up Jest for unit testing in a React Native project.

Think about installation, configuration, writing tests, and running them.

Describe how snapshot testing works with Jest in React Native.

Focus on rendering, saving, and comparing UI snapshots.