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 components that interact with APIs

This section will build on our knowledge of testing event handlers from the previous section by looking at how to test components that send and receive data from APIs. In our component unit tests, we can reduce application risk with our testing efforts by using tools that act as test doubles in place of real APIs. Using test doubles in place of the actual API, we can avoid slow internet connections or receive dynamic data resulting in unpredictable test results.

We will learn how to install and use Mock Service Worker (MSW) as a test double in tests to capture API requests initiated by our components and return mock data. We will test a component designed for users to search for drinks data from an API. We will also learn how to use MSW as a development server. The concepts in this section will help us understand how to verify communication between the frontend and API servers.

Requesting API data with fetch

We can create a component...