angular-cli/jasmine/karma/typescript - write a unit test

I have an angular-cli application where I need a unit test written for a service/method that makes a http get and receive an json array. The service/method is working when I run the application but I cannot work out how to write a test for it. If you have done this type of development before, I am sure it is a trivial tasks. I have just spend too much time already without getting it to work. I am new to angular-cli and therefore I am seeking help here. The application is being develop using vs code. I will provide access to a git repository where you can get the application code. The application is based on [login to view URL] This is the method that needs to be tested. getHierarchyItems(context: SiteContext): Observable<Array<HierarchyItem>> { return [login to view URL]([login to view URL](context), { cache: true }) .map((res: Response) => <Array<HierarchyItem>>[login to view URL]().HierarchyItems) .do(data => [login to view URL](data)) .catch([login to view URL]); } If need a test case where it compares a mock object against the data it receives from the live service (mock object already in the code) and a failure test.