The Angular testing utilities help to create a testing environment that makes writing tests for your various constructs really easy. It consists of the TestBed class and various helper functions, found under the @angular/core/testing namespace. We will learn what these are and how they can help us to test various constructs as this chapter progresses. We will shortly introduce the most commonly used concepts so that you are familiar with them as we present them more deeply further on:

• The TestBed class is the most important concept and creates its own testing module. In reality, when you test out a construct to detach it from the module it resides in and reattach it to the testing module created by the TestBed. The TestBed class has a configureTestModule() helper method that we use to set up the test module as needed. The TestBed can also instantiate components.
• ComponentFixture is a class wrapping the component instance. This means that it has some functionality on it and it has a member that is the component instance itself.  
• The DebugElement, much like the ComponentFixture, acts as a wrapper. It, however, wraps the DOM element and not the component instance. It's a bit more than that though, as it has an injector on it that allows us to access the services that have been injected into a component. More on this topic later.

This was a brief overview to our testing environment, the frameworks and libraries used, as well as some important concepts that we will use heavily in the upcoming sections.