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)

Using tests to catch regressions when updating dependencies

In this section, we will learn how to use tests to drive the updating of application dependencies. The tests will help verify that the application code continues to work as expected and allow us to quickly catch regressions if they occur after updating dependencies. The budgeting application renders the following when the application is running:

Figure 5.1 – Budget application

Figure 5.1 – Budget application

The preceding screenshot shows a summary section that includes Income, Spending, and Left over amounts based on user input. A user can click the SET INCOME button to update the value for Income:

Figure 5.2 – Setting the budget income

Figure 5.2 – Setting the budget income

The preceding screenshot shows a model that allows the user to enter and submit a number to update the value for Income. A user can also create budgets for various categories:

Figure 5.3 – Adding a budget category

Figure 5.3 – Adding a budget category

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