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

Fixing Cucumber tests by test-driving production code

In this section, we’ll start by doing a little up-front design, then we’ll write unit tests that cover the same functionality as the Cucumber tests, and then use those to build out the new implementation.

Let’s do a little up-front design:

  • When the user clicks on Start sharing, a dialog should appear with a Reset button.
  • If the user chooses to reset, the Redux store is sent a START_SHARING action with a new reset property that is set to true:
    { type: "START_SHARING", reset: true }
  • If the user chooses to share their existing commands, then the START_SHARING action is sent with reset set to false:
    { type: "START_SHARING", reset: false }
  • When the user clicks on Reset, a RESET action should be sent to the Redux store.
  • Sharing should not be initiated until after the RESET action has occurred.

That’s all the up-front design we need. Let’s move on to...