Book Image

Simplify Testing with React Testing Library

By : Scottie Crump
Book Image

Simplify Testing with React Testing Library

By: Scottie Crump

Overview of this book

React Testing Library (RTL) is a lightweight and easy-to-use tool for testing the document object model (DOM) output of components. This book will show you how to use this modern, user-friendly tool to test React components, reducing the risk that your application will not work as expected in production. The book demonstrates code snippets that will allow you to implement RTL easily, helping you to understand the guiding principles of the DOM Testing Library to write tests from the perspective of the user. You'll explore the advantages of testing components from the perspective of individuals who will actually use your components, and use test-driven development (TDD) to drive the process of writing tests. As you advance, you'll discover how to add RTL to React projects, test components using the Context API, and also learn how to write user interface (UI) end-to-end tests using the popular Cypress library. Throughout this book, you’ll work with practical examples and useful explanations to be able to confidently create tests that don't break when changes are made. By the end of this React book, you will have learned all you need to be able to test React components confidently.
Table of Contents (10 chapters)

Executing test cases with Jest

Jest is a JavaScript testing framework created by the team at Facebook. In this section, we will cover a brief overview of Jest and how we can use it to verify the output of test cases for React components.

Running tests with Jest

Most React projects are tested with Jest, so it makes sense to introduce this tool alongside learning React Testing Library. When we write our tests using React Testing Library, we need a test runner to execute the test.

Use the following command to install Jest in your project:

npm install --save-dev jest

We will run our React tests using Jest. At a high level, Jest provides the describe, it, test, and expect functions to organize and execute tests. You can think of the describe function as a test suite. Use the describe function to group related tests for specific components. The it and test functions are for specific tests. The it and test functions are interchangeable functions used to house and run the code...