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)

Testing user events

In this section, we will learn how to simulate user events and test the resulting output. To test component interactions, similar to the case with users, we need methods to simulate DOM events in our tests. Numerous events caused by users can occur on the DOM. For example, a user can perform a keypress event by entering text into an input box, a click event by clicking a button, or they can view drop-down menu items with a mouseover event. The DOM Testing Library provides two libraries to simulate user actions, fireEvent and user-event, which we are going to see in the following sections.

Simulating user actions with fireEvent

We can use the fireEvent module to simulate user actions on the resulting DOM output of components. For example, we can build a reusable Vote component that renders the following DOM output:

Figure 3.1 – Vote component

In the preceding screenshot, the number 10 represents the likes rating. We have two...