Book Image

Mastering React Test-Driven Development

By : Daniel Irvine
Book Image

Mastering React Test-Driven Development

By: Daniel Irvine

Overview of this book

Many programmers are aware of TDD but struggle to apply it beyond basic examples. This book teaches how to build complex, real-world applications using Test-Driven Development (TDD). It takes a first principles approach to the TDD process using plain Jest and includes test-driving the integration of libraries including React Router, Redux, and Relay (GraphQL). Readers will practice systematic refactoring while building out their own test framework, gaining a deep understanding of TDD tools and techniques. They will learn how to test-drive features such as client- and server-side form validation, data filtering and searching, navigation and user workflow, undo/redo, animation, LocalStorage access, WebSocket communication, and querying GraphQL endpoints. The book covers refactoring codebases to use the React Router and Redux libraries. via TDD. Redux is explored in depth, with reducers, middleware, sagas, and connected React components. The book also covers acceptance testing using Cucumber and Puppeteer. The book is fully up to date with React 16.9 and has in-depth coverage of hooks and the ‘act’ test helper.
Table of Contents (21 chapters)
Free Chapter
1
Section 1: First Principles of TDD
6
Section 2: Building a Single-Page Application
12
Section 3: Interactivity
16
Section 4: Acceptance Testing with BDD

Making asynchronous requests with sagas

The saga should perform all the same work as our existing doSave. That's what we'll build out in this section:

  1. In the same test file, add the following test to the saga describe block (the one named addCustomer, not the second reducer block you've just been working on). It doesn't look too different from anything we've seen before:
it('submits request to the fetch api', async () => {
const inputCustomer = { firstName: 'Ashley' };
dispatchRequest(inputCustomer);

expect(window.fetch).toHaveBeenCalledWith('/customers', {
body: JSON.stringify(inputCustomer),
method: 'POST',
credentials: 'same-origin',
headers: { 'Content-Type': 'application/json' }
});
});
  1. We'll need to define the spy on window.fetch for this to work. Change...