Book Image

Learning Angular - Fourth Edition

By : Aristeidis Bampakos, Pablo Deeleman
5 (1)
Book Image

Learning Angular - Fourth Edition

5 (1)
By: Aristeidis Bampakos, Pablo Deeleman

Overview of this book

As Angular continues to reign as one of the top JavaScript frameworks, more developers are seeking out the best way to get started with this extraordinarily flexible and secure framework. Learning Angular, now in its fourth edition, will show you how you can use it to achieve cross-platform high performance with the latest web techniques, extensive integration with modern web standards, and integrated development environments (IDEs). The book is especially useful for those new to Angular and will help you to get to grips with the bare bones of the framework to start developing Angular apps. You'll learn how to develop apps by harnessing the power of the Angular command-line interface (CLI), write unit tests, style your apps by following the Material Design guidelines, and finally, deploy them to a hosting provider. Updated for Angular 15, this new edition covers lots of new features and tutorials that address the current frontend web development challenges. You’ll find a new dedicated chapter on observables and RxJS, more on error handling and debugging in Angular, and new real-life examples. By the end of this book, you’ll not only be able to create Angular applications with TypeScript from scratch, but also enhance your coding skills with best practices.
Table of Contents (17 chapters)
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Testing services

As we learned in Chapter 6, Managing Complex Tasks with Services, a service can inject other services . Testing a standalone service is pretty straightforward: we get an instance from the injector and then start to query its public properties and methods.

We are only interested in testing the public API of a service, which is the interface that components and other artifacts use. Private symbols do not have any value in being tested because they represent the internal implementation of the service.

There are three different types of testing that we can perform in a service:

  • Testing a synchronous operation, such as a method that returns a simple array
  • Testing an asynchronous operation, such as a method that returns an observable
  • Testing services with dependencies, such as a method that makes HTTP requests

In the following sections, we will go through each of them in more detail.

Testing a synchronous method

When we create an Angular...