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

Selecting data to view

Let’s add in some dynamic behavior to our page. We’ll make each of the list items a link that the user can click on to view that appointment.

Thinking through our design a little, there are a few pieces we’ll need:

  • A button element within our li
  • An onClick handler that is attached to that button element
  • Component state to record which appointment is currently being viewed

When we test React actions, we do it by observing the consequences of those actions. In this case, we can click on a button and then check that its corresponding appointment is now rendered on the screen.

We’ll break this section into two parts: first, we’ll specify how the component should initially appear, and second, we’ll handle a click event for changing the content.

Initial selection of data

Let’s start by asserting that each li element has a button element:

  1. We want to display a message to the user...