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 use the Context API

In this section, we will learn how to test components that use the React library's Context API to manage state. The Context API helps solve issues related to passing props and methods multiple levels down the component tree, similar to Redux. The Context API allows you to directly send data to consumers without traveling through numerous parent-level components to get to the target consumer. An example application where the state could be more easily managed with the Context API is a website that allows users to change the theme from light to dark because multiple components would need to be aware when the theme changes. Another example would be a complex social networking site such as Twitter. Components that use Context must be used within the Context Provider component:

import { LikesProvider } from './LikesContext'
import Vote from './Vote'
const App = () => (
  <LikesProvider initialLikes=...