How to Test React Applications with Jest and React Testing Library

How to Test React Applications with Jest and React Testing Library

Learn how to test React applications with Jest and React Testing Library. Jest is a JavaScript testing framework that allows developers to run tests on JavaScript and TypeScript code and integrates well with React. React Testing Library is a JavaScript testing utility built specifically for testing React components.

Learn how to test React applications with Jest and React Testing Library, a popular combination and official recommendation from React.

Testing is an essential practice in software engineering. It helps build robust and high-quality software and boosts the team’s confidence in the code, making the application more flexible and prone to fewer errors when introducing or modifying features.

Highly efficient teams make testing a core practice in their everyday routines, and no feature is released before automated tests are in place. Some developers even write the tests before writing the features, following a process called TDD (Test Driven Development).

In this article, we’ll test React applications with Jest and React Testing Library, a popular combination of a JavaScript testing framework and a React utility for testing components. It’s also the official recommendation given on React’s documentation.

What is testing?

Testing is the process of automating assertions between the results the code produces and what we expect the results to be.

When testing React applications, our assertions are defined by how the application renders and responds to user interactions.

There are many different types of testing paradigms and philosophies. This article will focus on creating unit and component tests (or integration tests).

Introduction to Jest and React Testing Library

What is Jest?

Jest is a JavaScript testing framework that allows developers to run tests on JavaScript and TypeScript code and integrates well with React.

It’s a framework designed with simplicity in mind and offers a powerful and elegant API to build isolated tests, snapshot comparison, mocking, test coverage, and much more.

React Testing Library

React Testing Library is a JavaScript testing utility built specifically for testing React components. It simulates user interactions on isolated components and asserts their outputs to ensure the UI is behaving correctly.

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Unit Testing With Jest in Javascript,  — React

When you want to test some of your React components using Jest unit testing, there are a few extra steps that should be taken to ensure proper testing is completed. I would suggest reading part one to the series here before continuing on so that you get the basic knowledge and learn how to set things up before moving forward with this article.

Interaction Testing with React Testing Library

Testing is complicated. I’ve certainly never been good at it. For the longest time, I’ve only been focused on basic function input-output unit tests. Why? Because they were easy — you didn’t need to render HTML, you didn’t need to query DOM elements, you didn’t need to interact with said DOM elements. But of course, React component testing is a necessity for any mature codebase. And it finally came time for me to sit down and figure it out. A window into React component testing. Interaction Testing with React Testing Library

How to Test React Components using Jest

Introduces to Jest, a testing framework written by Facebook, with some great features that make it a breeze to test your React components. We’ll look at how we can use Jest first on plain JavaScript functions, before looking at some of the features it provides out of the box specifically aimed at making testing React apps easier.

Using Jest for React Snapshot Testing

Having trouble deciding between Jest and React for snapshot testing? The two most popular Jest screenshot testing libs for React today are jest-image-snapshot and react-screenshot-test. Take a look at this comparison of the two for help.