Jasmine/Karma- Writing Unit Test Cases for Angular

What is Jasmine? 

DOM-less simple JavaScript testing framework. Jasmine is a Behavior Driven Development testing framework for JavaScript. It does not rely on browsers, DOM, or any JavaScript framework. Thus, it's suited for websites, Node.js projects, or anywhere that JavaScript can run.

What is Karma? 

Spectacular Test Runner for JavaScript. Karma is not a testing framework, nor an assertion library. Karma just launches a HTTP server, and generates the test runner HTML file you probably already know from your favorite testing framework. So for testing purposes you can use pretty much anything you like

In short,

Jasmine: Javascript Testing Framework.  Can be used as TDD

Karma: Browser testing. Used as a Rest Runner

TESTING ANGULAR COMPONENTS

Consider the below angular component:

app.component.ts


app.component.spec.ts



TESTING SERVICES

Angular services contain UI-independent reusable business logic of the application.

myservice.service.ts


The spec file of this service has to contain:

HttpClientTestingModule and HttpTestingController for testing the behavior of HttpClient.

The HttpClientTestingModule includes a mock implementation of HttpClient service, which doesn’t make the actual XHR calls, instead it provides a way to inspect the calls attempted

The HttpTestingController provides APIs to make sure that the HTTP calls are made, to provide mock response to the calls and to flush the requests, so that the subscribers of the observables would be invoked

myservice.service.spec.ts



The above test calls the getPosts() method and expects a GET call to be made to the URL. Then it flushes the request with the data to be returned. This is when the call is completed and the subscribe method is called. At the end, it inspects if the request returned the correct data.


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