Feature Request

We are using azcosmos package to talk with CosmosDB. We are struggling with mock the cosmos client for unit test. I'm wonder if the azcosmos SDK could provide a easy way to mock.

I found a usefully example from Compute SDK as reference: https://github.com/Azure/azure-sdk-for-go/blob/fake_prototype/sdk/resourcemanager/compute/armcompute/README.md#fakes