Getting Started with Unit Test

How to setup and use Jest and Enzyme to test a React application created with Create React App (CRA)

Installation

npm install --save-dev enzyme enzyme-adapter-react-16

Step 1

Create a setupTests.js file at ./src/setupTests.js:

import { configure } from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';
configure({ adapter: new Adapter() });

Terms

Shallow

Renders only the single component, not including its children. This is useful to isolate the component for pure unit testing.

Jest will look for tests in any of the following places:

Files with .js suffix in tests folders. Files with .test.js suffix. Files with .spec.js suffix.