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

Switching component state for Redux state

The saga and reducer are now complete and ready to be used in the CustomerForm React component. In this section, we’ll replace the use of doSave, and then as a final flourish, we’ll push our React Router navigation into the saga, removing the onSave callback from App.

Submitting a React form by dispatching a Redux action

At the start of the chapter, we looked at how the purpose of this change was essentially a transplant of CustomerForm’s doSave function into a Redux action.

With our new Redux setup, we used component state to display a submitting indicator and show any validation errors. That information is now stored within the Redux store, not component state. So, in addition to dispatching an action to replace doSave, the component also needs to read state from the store. The component state variables can be deleted.

This has a knock-on effect on our tests. Since the saga tests the failure modes, our component...