Compare React Testing Library and Enzyme for Testing React Components.

React Testing Library and Enzyme are widely used testing utilities for React components. Although they serve the same purpose, their approaches and features differ.

React Testing Library

React Testing Library is a lightweight testing utility for React. It emphasizes testing components from the user's perspective. This means focusing on how users interact with the application and accessing the DOM elements in a way that resembles user behaviour.

Features of React Testing Library

• User Perspective Testing: React Testing Library helps you test your app like a real user. You check if buttons work, text boxes accept typing, and everything looks right for users.
• Interacting with DOM: It lets you interact with what's on your app's screen. You can click buttons, type text, and do other things users would do.
• Support for Delays: If your app needs to wait for something to happen, like getting data from a server, React Testing Library can handle that. It's good for testing components that use async operations.
• Tests That Don't Break Easily: React Testing Library looks at how your components behave instead of checking tiny details. This means your tests are less likely to break when you change your code.

Usage

React Testing Library is a popular library for testing React components. It focuses on testing components in a way that resembles how users interact with them, promoting better testing practices.

Installation Command:

Step 1: To install React Testing Library, run:

npm install react @testing-library/react @testing-library/jest-dom jest

Step 2: Set up Jest

• Create a file jest.config.js

// jest.config.js
module.exports = {  testEnvironment: 'jsdom',};

Step 3: Run the test

Run your test using Jest. Typically, this can be done by running:

npm test

Example: The example shows the implementation of React Testing Library.

import React from 'react';
import { render, screen, fireEvent } from '@testing-library/react';
import '@testing-library/jest-dom/extend-expect';

// Sample component
function Button({ onClick, children }) {
    return <button onClick={onClick}>{children}</button>;
}

// Test
test('button renders with correct text and handles click event', () => {
    const handleClick = jest.fn();
    render(<Button onClick={handleClick}>Click me</Button>);

    // Check if the button renders with the correct text
    expect(screen.getByText('Click me')).toBeInTheDocument();

    // Simulate a click event on the button
    fireEvent.click(screen.getByText('Click me'));

    // Verify if the click handler was called once
    expect(handleClick).toHaveBeenCalledTimes(1);
});

Output:

Enzyme

Enzyme, developed by Airbnb, is another testing utility for React. It offers various rendering strategies such as shallow rendering, full DOM rendering, and static rendering. Enzyme provides a rich set of utility functions for traversing and asserting on component output. Enzyme is another popular library for testing React components. It provides a more detailed and flexible API for interacting with components, supporting shallow rendering, full DOM rendering, and static rendering.

Features of Enzyme

• Shallow Rendering: Allows testing of a component in isolation by rendering only the component itself without its children, making it easier to test and debug.
• Full DOM Rendering: Provides the ability to render a component and its children, enabling more comprehensive testing that involves the full component tree.
• Static Rendering: Generates HTML from a component without running its lifecycle methods, useful for testing the output of simple components.
• Simulating Events: Provides methods to simulate user interactions like clicks, form submissions, and more, to test how components respond to events.
• Finding Elements: Offers intuitive methods to search for and find components and elements within the rendered output, making it easy to assert that the right elements are present and in the expected state.

Installation Command

Run the below command to install Enzyme:

npm install react enzyme enzyme-adapter-react-16 jest

Example: The example below shows how to set up Enzyme configuration

// setupTests.js
import { configure } from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';

configure({ adapter: new Adapter() });

import { shallow } from 'enzyme';

test('button renders with correct text and handles click event', () => {
  const wrapper = shallow(<button onClick={() => {}}>Click Me</button>);
  wrapper.simulate('click');
});

Run the below command:

npm test

Difference between React Testing Library and Enzyme

The table below describe the difference between React Testing Library and Enzyme:

Conclusion

React Testing Library and Enzyme serve similar purposes but with different philosophies. React Testing Library focuses on user-centric testing, while Enzyme provides a rich set of utilities for component-centric testing. Choose the tool that aligns best with your project requirements and testing philosophy.