Unit test a service with http request only angularjs - angularjs

Question

I have a function called getFrame in a service. The function just returns the $http call to controller.
angular.module('app').factory('DemoFactory', function ($http) {
function getFrame(id) {
var url = 'http://localhost:8080/frames/' + id + '/';
return $http.get(url);
}
return {
getFrame: getFrame
};
});
Now I want to write unittest for this which I am doing as follows:
describe('Service: DemoFactory', function () {
// load the service's module
beforeEach(module('app'));
// Instantiate service
var $httpBackend,
DemoFactory;
beforeEach(inject(function (_$httpBackend_, _DemoFactory_) {
$httpBackend = _$httpBackend_;
DemoFactory = _DemoFactory_;
}));
it('should send proper http request from getFrame', function () {
$httpBackend.expectGET('http://localhost:8080/frames/1/').respond(200);
DemoFactory.getFrame(1);
$httpBackend.flush();
});
afterEach(function () {
$httpBackend.verifyNoOutstandingExpectation();
$httpBackend.verifyNoOutstandingRequest();
});
});
With the given service my aim is to test whether getFrame is making a proper http request or not. So I think I am doing OK here. But something made me wonder that it block is not having any expect. So I need to confirm that for the service I have written I can have unit test as described. Do I need to have anything else in the unit test or can I do it any other way?