Mock GetMessage() method of azure queue.

Hello ,
I am uisng azure queue for message sorage. Now I want to test their wiorking.
Could u please tell me hta how do I mock the queue.AddMessage() & queue.GetMessage() methods for azure queue?

----Code----
1. CloudQueueMessage msg = new CloudQueueMessage("Message");
2. CloudQueue queue = Isolate.Fake.Instance<CloudQueue>(Members.MustSpecifyReturnValues);

3. Isolate.Swap.AllInstances<CloudQueue>().With(queue);
4. Isolate.WhenCalled(() => queue.GetMessage()).WillReturn(msg);
-----------Code---------

In above code , code line 4 is not returning the "msg" object when i run the test.