Simplified Angular unit testing In this article, we will learn how to write (simple) unit tests for your Angular modeling blocks (service, component, async task, etc.). We can use spies to test components that depend on a service and avoid actually calling the service’s methods to get a value. Angular was designed with testability in mind and it provides multiple options to support Unit Testing.In this article I will show you how you can setup Jasmine and write unit tests for your angular components. First off, we are importing two more dependencies from Angular’s core library — Input and OnInit. Let’s say an HTML text input is simply sitting there, waiting for the user to click the form’s submit button, after which your JavaScript code would take that text input’s value and send it as part of the HTTP POST request. These articles are not intended to be comprehensive, rather a soft introduction to unit testing. This uses a spy implementation of Location which doesn’t trigger a request for a new URL but does let us know the target URL which we can use in our test specs. By using the ATB and fixtures we can inspect the component’s view through fixture.debugElement and also trigger a change detection run by calling fixture.detectChanges(). We can test routing in Angular by using RouterTestingModule instead of RouterModule to provide our routes. Input is a decorator that lets Angular know that an attribute of our class is a data-bound input property. Whether these are unit tests, integration or e2e tests. For this reason we feel very strongly that any code written in JavaScript needs to come with a strong set of tests. It will invoke the event handler only if it was declared on the native element by using Angular event bindings, … This helps keep our unit tests focused on testing the internals of the component itself instead of its dependencies. Angular provides lifecycle hooks for change detection. It is done during the development of any application. Next up we’ll look at how to can test asynchronous functions in Angular. In Angular 8, Unit testing created with the help of Angular CLI. Unit Testing JavaScript is a dynamically typed language which comes with great power of expression, but it also comes with almost no help from the compiler. A lot has changed here. One of the interesting additions that came about with the HttpClient in Angular is the HttpClientTestingModule.. We have a simple test for a component that, upon a click, sets an emoji. To test directives we use dummy test components which we can create using the Angular Test Bed and which we can interact with by using a component fixture. Listing 1. router.ts. We use the query() method to obtain a reference to the element and triggers the click event handler using the triggerEventHandler() method.. Three important facts about the triggerEventHandler() method:. Whenever parent component changes the value of properties used in … If a parent component was to use the following markup: