Top React Testing Libraries you should know about

In recent years, React, a widely-used JavaScript library, has emerged as a leading framework for web development. As the complexity of React applications increases, the demand for thorough testing will rise correspondingly.

The React community has developed several libraries to facilitate the testing of React components, enabling developers to efficiently write and execute tests. These libraries offer a range of features, from basic unit testing to comprehensive end-to-end testing, simplifying the process of evaluating various aspects of your application. However, with so many options available, selecting the appropriate testing framework for your project can be daunting.

As we progress into 2023, staying current with the latest and most robust testing libraries and tools in the React ecosystem is crucial. In this article, we'll review some of the top React testing libraries and frameworks that developers can utilize to ensure their applications are free of bugs and perform optimally.

1. Jest

Jest has established itself as one of the most popular React testing frameworks available today. Developed by Facebook, Jest is designed to offer a seamless testing experience for React developers. Its versatility is highlighted by its support for TypeScript, Node.js, Angular, and Vue.js, in addition to React. Jest is the preferred testing framework for many major companies, including Uber, Airbnb, and Facebook, which adds to its popularity among React developers. This React library includes features like UI snapshot testing, code coverage, and an extensive API tailored to React, making it a favorite in the React community.

One of Jest's significant advantages is its out-of-the-box support for most JavaScript projects, including create-react-app, NG, Vue, TypeScript, and Babel, which saves developers time and effort. Furthermore, Jest's process-based parallel testing feature is user-friendly and allows for the prioritization of failed tests. Another notable aspect of Jest is its ease of use; setting up Jest is straightforward, and it is readily available on Node Package Manager (NPM). Developers familiar with JavaScript can quickly start writing Jest tests without much hassle.

Jest's comprehensive features, ease of use, and performance benefits make it a leading React testing library. With over 16 million downloads per week, it's no surprise that Jest is the most popular testing framework for React.

Why is Jest popular?

• The Jest snapshot capturing feature simplifies tracking large test cases.
• Jest supports parallelization and async method tests, resulting in faster and more efficient testing processes.
• Its popularity is further boosted by its ease of use and zero setup requirement, making it accessible to developers of all skill levels.
• its excellent performance and standard syntax, Jest provides a comprehensive report guide, aiding in the understanding and analysis of test results.

Installation

An installation using yarn.

yarn add --dev jest

An installation using npm.

npm install --save-dev jest

2. React Testing Library

React Testing Library is a widely-used testing library favored by companies such as Graphy, Ze Delivery, Commercetools, Hivebrite, MPB, and Page Builder. The library is designed to simulate user behavior in tests, making it easier to test components accurately. It offers a comprehensive set of React DOM testing utilities that allow developers to replicate real user actions and workflows, facilitating the testing of React components.

Built on top of the DOM Testing Library, React Testing Library provides a set of utilities for testing React components in a way that closely mimics user interaction with the application. One of its main advantages is the simple and intuitive API, which enables developers to focus on testing component behavior rather than implementation details. This approach results in more resilient tests that are less likely to break due to changes in implementation.

While React Testing Library has some limitations, such as the inability to perform shallow rendering or access state-based information, it remains an excellent solution for testing components from the user's perspective. Its popularity in the React community underscores its effectiveness as a choice for testing React components.

Why is React Testing Library popular?

• Developers can use utilities to easily write tests in React Testing Library, without any experience with testing frameworks.
• It is well-suited for unit and integration testing, offering a comprehensive set of DOM testing utilities.
• It can be seamlessly integrated with popular frameworks like React, Angular, and Vue, making it a versatile option for testing various types of applications.
• One of its most significant advantages is that refactoring components does not break the tests.
• It is backed by a large community of developers who actively contribute and support the library.

Here’s a good read on How to Migrate from Enzyme to React Testing Library!

Installation

npm installation

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

Yarn installation

yarn add --dev @testing-library/react

3. Enzyme

Enzyme is a widely recognized testing utility that streamlines the testing of React components by abstracting the rendering process. This framework is frequently used alongside Jest, but other React testing libraries such as Karma and Mocha also incorporate Enzyme. Its capability to manipulate, traverse, and simulate runtime components makes it a potent tool for locating and interacting with DOM elements.

Similar to how JQuery manipulates DOM elements, Enzyme can also handle, traverse, and even simulate runtime elements. Companies like Frontend, BlaBlaCar, and Kaidee utilize Enzyme for testing their applications, with Airbnb being a major contributor and maintainer, as well as incorporating it into their workflows. Overall, Enzyme is an outstanding choice for developers seeking a robust and user-friendly tool for testing their React components.

Why is Enzyme popular?

• Enzyme is easy to use and works smoothly with testing libraries like Jest, Mocha, and Karma, making it the top choice for testing almost one-third of React applications.
• Enzyme offers shallow rendering and full DOM rendering options for testing React components.
• With Enzyme, developers can access React components to conduct testing.
• The utility provides detailed error reporting that helps with identifying and resolving issues quickly.

Installation

To begin using the enzyme, one simply needs to install it using the npm package manager. However, if one is using React or another UI Component library, one will also need to install an adapter along with enzyme. Enlisted below is an example of how to use enzyme with React 16:

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

Each adapter that is in use may have additional peer dependencies, so one may need to install them as well.

One major drawback of Enzyme is that it only supports up to React 16. Enzyme has not been updated to support newer versions of React such as React 18, which introduced improvements like automatic batching, fresh new APIs like startTransition, and also streaming server-side rendering with support for Suspense.

4. Cypress

Cypress is an end-to-end testing framework designed to simplify and enhance the setup, writing, execution, and debugging of browser tests for any front-end framework. Built on Mocha, a comprehensive JavaScript test framework that operates in the browser, Cypress facilitates asynchronous testing. It includes a behavior-driven development (BDD) and test-driven development (TDD) assertion library, compatible with any JavaScript testing framework. Cypress allows developers to swiftly write and execute tests, utilizing familiar APIs and native browser features like automated screenshots, real-time reloading, and network traffic control.

A standout feature of Cypress is its capability to run tests directly in the browser, enabling easy and efficient test debugging. This makes Cypress an excellent choice for web application testing, as it allows developers to simulate real-world scenarios and interactions within the browser environment. Furthermore, Cypress offers a user-friendly interface that lets developers write and execute tests using various tools, including the Cypress Test Runner, a command-line interface (CLI), and an integrated development environment (IDE) plugin.

In summary, Cypress is a reliable and efficient testing framework that streamlines the testing process, making it easier for developers to ensure the quality and reliability of their front-end applications.

Why is Cypress popular?

• Easy to setup and run tests.
• Low test writing time as compared to other frameworks.
• Integrates with any CI tool that supports headless execution with command-line options.
• Automatically captures screenshots of test execution in case of test failure for effective debugging.
• Automatically reloads the Test Runner once changes have been made to the test.

Installation

npm installation for Macs, Linux and Windows

npm install cypress --save-dev

Yarn install

yarn add cypress --dev

5. Mocha

Mocha is a JavaScript testing framework compatible with both Node.js and web browsers. It supports asynchronous testing and provides detailed reporting by executing tests sequentially. Mocha also links any uncaught exceptions to the relevant test cases, enhancing error tracking. Its flexibility allows developers to customize their testing tools and decide which supporting libraries to include or exclude.

Mocha can be paired with libraries like Enzyme and Chai for assertions and mocking when testing React applications, similar to other frameworks like Jest. However, some developers prefer using Mocha with a comprehensive toolset for more advanced configurations. One disadvantage of using Mocha for React testing is the potential need for additional tools in the workflow to handle common tasks such as snapshots.

Why is Mocha popular?

• Supports testing of asynchronous code
• Can be used for testing both server-side and client-side applications
• Offers high flexibility for customization and configuration
• Has extensive documentation and a wide range of tutorials available for learning and troubleshooting

Installation

With npm, install globally:

$ npm install --global mocha

You can use these development dependencies in your project:

$ npm install --save-dev mocha

6. Karma

Karma enables the real-time execution and testing of JavaScript programs across multiple browsers. It allows tests to be run on actual browsers and devices, including mobile phones, tablets, and desktops, with feedback delivered directly to your IDE. The Karma test runner operates on an HTTP server that generates the HTML file needed for testing. Additionally, it integrates seamlessly with continuous deployment tools like Jenkins, Travis, and others.

Karma is compatible with React testing frameworks and assertion libraries, and it also works effectively with Jasmine, Mocha, and similar libraries.

Why is Karma popular?

• Karma allows performing cross-browser testing.
• Supports continuous integration and deployment to Jenkins, Travis, and CircleCI.
• Provides an easy and seamless way to write code and obtain feedback from tests
• Has extensive community support and numerous plugins available

Installation

The Karma package runs on Node.js and is accessible via npm. To install Karma and its required plugins in your project directory, follow the steps below for a local installation. Karma must be installed by:

$ npm install karma --save-dev

If your project requires plugins, install them as follows:

$ npm install karma-jasmine karma-chrome-launcher jasmine-core --save-dev

7. Chai

Chai is an assertion library for JavaScript that provides a wide range of assertion styles and interfaces. It can be used for testing any JavaScript code, not just React components.

Why is Chai popular?

• Easy to use and learn.
• Lightweight and makes it easy to integrate into existing projects.
• Compatible with any testing framework and can be easily customized to meet specific testing requirements.

Installation

First, we will install the Chai library using npm:

npm install chai

We can also use yarn to install Chai, the code snippet is:

yarn add chai

8. Puppeteer

Puppeteer is a Nodejs library which was developed by Google and lets you control headless Chrome, which is a way of running chrome without a Graphical User Interface, through the dev tools Protocol. It also provides a high-level API for controlling a headless Chrome browser, which makes it easy to simulate user interactions and test the behaviour of your React components.

Why is Puppeteer popular?

• It allows for the testing of both client-side and server-side rendering of React components.
• Puppeteer can be used to test complex user flows that involve multiple pages and interactions.
• The library provides powerful debugging tools that make it easy to diagnose and fix issues in your tests.
• Puppeteer has built-in support for testing accessibility features of your React components.

Installation

To install Puppeteer, you can use npm:

npm i puppeteer

After installation, you can use Puppeteer in your tests by requiring it:

const puppeteer = require('puppeteer');

9. Jasmine

Jasmine is a well-known testing framework that is suitable for testing React applications. It offers a user-friendly and straightforward API for creating tests and has a significant community of contributors that participate in its advancement.

Why is Jasmine popular?

• Jasmine provides a BDD-style syntax that is easy to read and write, making it easy to write tests for React components.
• The framework supports both synchronous and asynchronous testing.
• Jasmine provides a range of built-in matchers that makes it easy to test the behavior of React components.
• The framework has a large and active community of developers, which means that there are many resources available for learning about this library.

Installation

To install Jasmine, you can use npm:

npm install --save-dev jasmine

After installation, you can use Jasmine in your tests by creating a spec file:

describe('My React Component', () => {
  it('should render correctly', () => {
    // Write your test code here
  });
});

10. React Test Utils

React Test Utils provides a simple and intuitive API for testing React components, and is built on top of the React library itself, which means that it is tightly integrated with React and is optimized for testing React components.

Why is React Test Utils popular?

• React Test Utils provides a range of built-in utilities for testing React components, including shallow rendering and simulation of user interactions.
• The library provides a simple and intuitive API that is easy to learn and use.
• It is built on top of the React library, which means it is tightly integrated with React and is optimized for testing React components.
• The library is compatible with other testing frameworks, such as Jasmine and Mocha.

Installation

To install React Test Utils, you can use npm:

npm install react-test-utils --save-dev

After installation, you can use React Test Utils in your tests by requiring it:

const ReactTestUtils = require('react-test-utils');

11. Test Renderer

Test Renderer is basically a React renderer that is generally used to render React components to pure JavaScript objects, without solely depending on the DOM or a native mobile environment.

It also provides a lightweight and simple API for testing React components. It is designed to be used in conjunction with Jest, but can also be used with other testing frameworks.

Essentially, this package makes it easy to grab a snapshot of the platform view hierarchy (similar to a DOM tree) rendered by a React DOM or React Native component without using a browser or jsdom.

Why is Test Renderer popular?

• Test Renderer provides a lightweight and simple API that is easy to use and understand.
• The library is designed to work with React's virtual DOM, which makes it an excellent tool for testing React components that do not require a full DOM environment.
• Test Renderer is compatible with Jest, a popular testing framework for React applications, which means that it can be easily integrated into existing test suites.
• The library is also compatible with other testing frameworks, such as Mocha and Jasmine.

Installation

To install Test Renderer, you can use npm:

npm install react-test-renderer --save-dev

After installation, you can use Test Renderer in your tests by requiring it:

const TestRenderer = require('react-test-renderer');

Conclusion

Developers have too many choices when it comes to selecting a React testing library for their applications. Settling down with a single library can be a hard call, but you don't have to take it. You can combine these testing frameworks and assertion/manipulation libraries to create test-driven development with a flexible and adaptable workflow.

If you are starting with React, generally speaking, React testing library can be your go-to framework. But that should not stop you from experimenting with other libraries as you grow.

Now that you have a decent understanding of React testing libraries, a good next step would be to learn how to write Unit Tests for your React app!

Happy coding!