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

Spying on the fetch API

In this section, we’ll use the Fetch API to send customer data to our backend service. We already have an onSubmit prop that is called when the form is submitted. We’ll morph this onSubmit call into a global.fetch call, in the process of adjusting our existing tests.

In our updated component, when the Submit button is clicked, a POST HTTP request is sent to the /customers endpoint via the fetch function. The body of the request will be a JavaScript Object Notation (JSON) object representation of our customer.

The server implementation that’s included in the GitHub repository will return an updated customer object with an additional field: the customer id value.

If the fetch request is successful, we’ll call a new onSave callback prop with the fetch response. If the request isn’t successful, onSave won’t be called and we’ll instead render an error message.

You can think of fetch as a more advanced form...