Book Image

Mastering React Test-Driven Development - Second Edition

By : Daniel Irvine
Book Image

Mastering React Test-Driven Development - Second Edition

By: Daniel Irvine

Overview of this book

Test-driven development (TDD) is a programming workflow that helps you build your apps by specifying behavior as automated tests. The TDD workflow future-proofs apps so that they can be modified without fear of breaking existing functionality. Another benefit of TDD is that it helps software development teams communicate their intentions more clearly, by way of test specifications. This book teaches you how to apply TDD when building React apps. You’ll create a sample app using the same React libraries and tools that professional React developers use, such as Jest, React Router, Redux, Relay (GraphQL), Cucumber, and Puppeteer. The TDD workflow is supported by various testing techniques and patterns, which are useful even if you’re not following the TDD process. This book covers these techniques by walking you through the creation of a component test framework. You’ll learn automated testing theory which will help you work with any of the test libraries that are in standard usage today, such as React Testing Library. This second edition has been revised with a stronger focus on concise code examples and has been fully updated for React 18. By the end of this TDD book, you’ll be able to use React, Redux, and GraphQL to develop robust web apps.
Table of Contents (26 chapters)
Part 1 – Exploring the TDD Workflow
Part 2 – Building Application Features
Part 3 – Interactivity
Part 4 – Behavior-Driven Development with Cucumber

Indicating form submission status

It’d be great if we could indicate to the user that their form data is being sent to our application servers. The GitHub repository for this book contains a spinner graphic and some CSS that we can use. All that our React component needs to do is display a span element with a class name of submittingIndicator.

Before we write out the tests, let’s look at how the production code will work. We will introduce a new submitting boolean state variable that is used to toggle between states. It will be toggled to true just before we perform the fetch request and toggled to false once the request completes. Here’s how we’ll modify handleSubmit:

if (!anyErrors(validationResult)) {
  const result = await global.fetch(...);

If submitting is set to true, then we will render the spinner graphic. Otherwise, we will render nothing...