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.

Preface

Who this book is for?

What this book covers?

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Conventions used

Chapter 1: Exploring React Testing Library

Chapter 1: Exploring React Testing Library

Technical requirements

Introducing the DOM Testing Library

Executing test cases with Jest

Enhancing Jest assertions with jest-dom

Testing implementation details

Free Chapter

Chapter 2: Working with React Testing Library

Chapter 2: Working with React Testing Library

Technical requirements

Adding React Testing Library to existing projects

Structuring tests with React Testing Library

Testing presentational components

Using the debug method

Chapter 3: Testing Complex Components with React Testing Library

Chapter 3: Testing Complex Components with React Testing Library

Technical requirements

Testing user events

Testing components that interact with APIs

Implementing test-driven development

Chapter 4: Integration Testing and Third-Party Libraries in Your Application

Chapter 4: Integration Testing and Third-Party Libraries in Your Application

Technical requirements

Testing integrated components

Testing components that use the Context API

Testing components that use Redux

Testing components that use GraphQL

Testing Components that use Material-UI

Chapter 5: Refactoring Legacy Applications with React Testing Library

Chapter 5: Refactoring Legacy Applications with React Testing Library

Technical requirements

Using tests to catch regressions when updating dependencies

Refactoring tests written with Enzyme

Refactoring tests written with ReactTestUtils

Refactoring tests to comply with common testing best practices

Chapter 6: Implementing Additional Tools and Plugins for Testing

Chapter 6: Implementing Additional Tools and Plugins for Testing

Technical requirements

Implementing best practices with Testing Library ESLint plugins

Testing accessibility with jest-axe

Selecting the best queries with Testing Playground

Increasing our testing productivity with Wallaby.js

Chapter 7: End-to-End UI Testing with Cypress

Chapter 7: End-to-End UI Testing with Cypress

Technical requirements

Getting started with Cypress

Enhancing Cypress commands with the Cypress Testing Library

Cypress-driven development

Writing Tests using Cypress design patterns

Testing APIs with Cypress

Writing Gherkin-style tests with Cucumber

Using React Developer Tools with Cypress

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What this book covers?

Chapter 1, Exploring React Testing Library, will help you understand the guiding principles of the DOM Testing Library to write tests from the perspective of the user. You will learn the disadvantages of implementing detail-focused testing. Finally, you will learn the advantages of using jest-dom to enhance our tests using RTL.

Chapter 2, Working with React Testing Library, will teach you how to add RTL to React projects. You will learn how to properly structure tests using the API. You will look at presentational components and write some initial tests. Finally, we will learn how to use the debug method to assist us in the process of writing tests.

Chapter 3, Testing Complex Components with React Testing Library, will help you understand how to test more complex React components. You will learn how to simulate user interactions with Fire Event and the user event module. You will learn how to use TDD to drive the process of writing tests. Finally, you will unit test components that interact with APIs.

Chapter 4, Integration Testing and Third-Party Libraries in Your Application, teaches you how to test components in various React applications. You will learn how to test integrated components and how to test components using the Context API. Finally, you will test components using popular third-party libraries such as GraphQL and Redux.

Chapter 5, Refactoring Legacy Applications with React Testing Library, will teach you strategies for dealing with breaking changes while refactoring legacy React applications. You will learn how to update production packages while using RTL tests to guide you in resolving breaking changes. You will also learn how to convert tests written in Enzyme or ReactTestUtils to RTL.

Chapter 6, Implementing Additional Tools and Plugins for Testing, will help you learn additional tools to enhance your ability to test React applications using RTL.

Chapter 7, End-To-End UI Testing with Cypress, will teach you how to write end-to-end UI tests using the popular Cypress library. You will learn design patterns to structure your tests. You will learn how to test APIs with Cypress. Finally, you will learn how to integrate Cucumber and React Developer Tools into your test suite.