React js testing – Tools & Libraries for Testing

Hey readers, in this article we will be deep diving about the testing tool in React js. Previously we have done many blogs related to React js fundamentals, working, and advanced concepts, so if you haven’t checked it out yet, do it now on the codedamn blog section.

If you are a developer, then you might probably have used React js in your application for building the frontend. While building, there are some tools that are the developer’s favorite when it comes to testing the React application. However different tools serve different use cases depending on the framework used in the application, hence it is advisable to choose the right tool by learning about the application. Whether it’s testing, integration testing, or end-to-end testing, we will cover everything in this article.

Here are some of the most popular testing tool used.

Jest

It is the most popular tool when it comes to testing React framework with 16+Million downloads per week. Jest is maintained and developed by Meta (previously Facebook).  Developers use this to test applications built using React and JavaScript. It is currently used by Airbnb, Intuit, Uber, etc. Jest has in-built assertion functions and a test runner. 

Advantages:

• Increased performance, Airbnb tested it and their application saw a fast performance from 12 mins to 4.5 mins.
• Jest is compatible with Vue, React, Angular
• Using live snapshot, it is possible  to manage larger objects
• Provides report guide with a standard syntax
• Parallelization and async method tests

Mocha

It is another popular testing tool for JavaScript developers. It provides us with browser support for Node js, reports of test coverage, synchronous test,s, etc. Apart from this, it allows full control over testing of the code, a variety of tool options as well as the support of libraries and tools that developers can use. Mocha is an alternative option to that of Jest issues like mocking which is why Mocha is used.

Advantages

• It runs on Node js and supports testing for asynchronous front-end and back-end
• Error tracking
• Mocha + Enzyme makes a good combination for test React web application
• Combination of Mocha +  Chai is popular for the mocking, assertion, etc

Chai

It is a popular assertion library for Node as well as for browsers that can be paired with the JavaScript framework of any type. Since Mocha doesn’t have an assertion library, Chai along with Mocha is used for testing React web applications. Functionalities assert helps to declare what to expect in a test. It can be used to make assertions for function as well as components by using Enzyme. 

Jasmine

 It is a Behaviour Driven Development (BDD) open-source framework and test runner for testing all types of JavaScript applications. The test includes a visibility and response test of the user interface on different devices and resolutions. It is most popular for Angular developers who use Angular CLI. Developers mostly use it by combining Enzyme and Babel to test React js applications.

Advantages

• A DOM is also known as Document object model is not required for Jasmine
• It is helpful in both front-end as well as backend tests
• Can be used to test async functions as well as mock requests
• It provides custom equality checker assertion and custom matcher assertion
• It also provides easy to understand documentation as well as community support

Enzyme

It is a testing tool designed to help developers for testing components in React without any difficulty. It is maintained by Airbnb and is one of the most used frameworks. It can be combined with other frameworks like Jest, Mocha, and Chai to test React applications. It is used to render components, find and interact with elements and stimulate an event. 

Advantage

• Shallow rendering
• Accessing business implementation of component
• Full DOM rendering
• Can use React Hook for shallow rendering

1. Cypress I/O- It is a very fast and to end testing framework that helps us to write tests without using any other framework. Tests can be run in a browser along with browser tools side by side or command line. It comes with a control panel and gives us control over tests status.

Advantages

• Screenshots and videos along with snapshots
• Automatic waiting and network control
• To make debugging easy, it has an in-built parallelization and load balancer

React-testing-library

 It is created by Kent C.Dodds. It allows to test components with ease and to stimulate user behavior in it. Just like enzyme, this library consists of a complete set of React DOM testing utilities which is used user action and workflow. 

Advantage

• Can be used for querying an element within text, displayVlaue, label, role, and testId
• Fire an event in an application
• Wait for an element to appear along with wait

Puppeteer

It is not a JavaScript framework but a headless chromium Node library that provides API  to control chrome through DevTool protocol. By using this, we can navigate between pages with the API provided, get buttons, click on them and start chromium. Apart from this, it can also be used for generating pre define content from SPA, generating screenshots, actions like form submission, etc. 

Advantage

• Automated UI test
• Screenshots and pdf files creation of web page
• Testing for chrome extensions

Conclusion

Each testing library has its own use cases so choose according to your requirements of an application.  Do let us know in the comment section if you have any queries. If you are interested in learning React js, do check out courses on codedamn with an in-built environment playground to learn and practice code. Join the community of codedamn and do check out other articles of programming and YouTube channel for content related to programming language and development on codedamn.