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

Chapter 8. Writing Unit/Integration Tests

We have now done as much as we can to modularize our code base, but how much confidence do we have in each of the modules? If one of the E2E tests fails, how would we pinpoint the source of the error? How do we know which module is faulty?

We need a lower level of testing that works at the module level to ensure they work as distinct, standalone units—we need unit tests. Likewise, we should test that multiple units can work well together as a larger logical unit; to do that, we need to also implement some integration tests.

By following this chapter, you will be able to do the following:

  • Write unit and integration tests using Mocha
  • Record function calls with spies, and simulate behavior with stubs, both provided by the Sinon library
  • Stub out dependencies in unit tests using dependency injection (DI) or monkey patching
  • Measuring test coverage with Istanbul/nyc