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)

Implementing test-driven development

Test-Driven Development (TDD) entails writing unit tests first and then building the code to pass. The TDD approach allows you to think about whether the code is correct for the tests you want to write. The process provides a perspective that focuses on the least amount of code needed to make tests pass. TDD is also known as Red, Green, Refactor. Red represents failing tests, Green represents passing tests, and as the name says, Refactor means refactoring the code while maintaining passing tests. A typical TDD workflow would be the following:

  1. Write a test.
  2. Run the test, expecting it to fail.
  3. Write the minimum amount of code to make the test pass.
  4. Rerun the test to verify it passes.
  5. Refactor the code as needed.
  6. Repeat steps 2 through 5 as needed.

We can use React Testing Library to drive the development of React components using the TDD approach. First, we will use TDD to build the Vote component we introduced...