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

Variants of the jest.mock call

Before we finish up this chapter, let’s take a look at some variations on the jest.mock call that you may end up using.

The key thing to remember is to keep your mocks as simple as possible. If you start to feel like your mocks need to become more complex, you should treat that as a sign that your components are overloaded and should be broken apart in some way.

That being said, there are cases where you must use different forms of the basic component mock.

Removing the spy function

To begin with, you can simplify your jest.mock calls by not using jest.fn:

jest.mock("../src/AppointmentsDayView", () => ({
  AppointmentsDayView: () => (
    <div id="AppointmentsDayView" />

With this form, you’ve set a stub return value, but you won’t be able to spy on any props. This is sometimes useful if, for example, you’ve got multiple files...