AngularJS unit testing: Constructor Test: Windows Azure Invoke Api

I am making an Hybrid App using Ionic(AngularJS). I have a generic factory which uses an invoke Api method of WindowsAzureService JS SDK. And I am unit testing my application.

var mClient = new WindowsAzure.MobileServiceClient(applicationUrl,applicationKey);

mClient.invokeApi(api, data, header)).done(function (res) {
   // do something 
})

I am not using $http, so I can't mock test cases with a $httpBackend. I would like some help on how to test api calls using windowsAzureServices.

Also how to I spyOn this constructor?

Github link to SDK