Exception thrown by mocks when setups are not matched, the mock is not properly setup, etc.

[SerializableAttribute]
public class MockException : Exception

A distinct exception type is provided so that exceptions thrown by the mock can be differentiated in tests that expect other exceptions to be thrown (i.e. ArgumentException).

Richer exception hierarchy/types are not provided as tests typically should not catch or expect exceptions from the mocks. These are typically the result of changes in the tested class or its collaborators implementation, and result in fixes in the mock setup so that they dissapear and allow the test to pass.

System..::..Object
  System..::..Exception
    Moq..::..MockException