Book Image

Building Enterprise JavaScript Applications

By : Daniel Li
Book Image

Building Enterprise JavaScript Applications

By: Daniel Li

Overview of this book

With the over-abundance of tools in the JavaScript ecosystem, it's easy to feel lost. Build tools, package managers, loaders, bundlers, linters, compilers, transpilers, typecheckers - how do you make sense of it all? In this book, we will build a simple API and React application from scratch. We begin by setting up our development environment using Git, yarn, Babel, and ESLint. Then, we will use Express, Elasticsearch and JSON Web Tokens (JWTs) to build a stateless API service. For the front-end, we will use React, Redux, and Webpack. A central theme in the book is maintaining code quality. As such, we will enforce a Test-Driven Development (TDD) process using Selenium, Cucumber, Mocha, Sinon, and Istanbul. As we progress through the book, the focus will shift towards automation and infrastructure. You will learn to work with Continuous Integration (CI) servers like Jenkins, deploying services inside Docker containers, and run them on Kubernetes. By following this book, you would gain the skills needed to build robust, production-ready applications.
Table of Contents (26 chapters)
Title Page
Copyright and Credits
Packt Upsell
Free Chapter
The Importance of Good Code

Unit testing the request handler

First, we'll move the src/handlers/users/create.js module into its own directory. Then, we will correct the file paths specified in the import statements to point to the correct file. Lastly, we will create an index.unit.test.js file next to our module to house the unit tests.

Let's take a look at the createUser function inside our request handler module. It has the following structure:

import create from '../../../engines/users/create';
function createUser(req, res, db) {
  create(req, db)
 .then(onFulfilled, onRejected)

First, it will call the create function that was imported from src/engines/users/create/index.js. Based on the result, it will invoke either the onFulfilled or onRejected callbacks inside the thenblock.

Although our createUser function depends on the create function, when writing a unit test, our test should test only the relevant unit, not its dependencies. Therefore, if the result of our tests relies on thecreate function, we...