This line of code:
Isolate.Swap .NextInstance<FileStream>().With(Isolate.Fake.Instance<FileStream>());
Will throw this exception:
failed: TypeMock.TypeMockException :
*** In order to perform swapping the call to NextInstance<T>() must be completed by a call to With()
at TypeMock.MockManager.a(String A_0, String A_1, Object A_2, Object A_3, Boolean A_4, Object[] A_5)
at TypeMock.InternalMockManager.getReturn(Object that, String typeName, String methodName, Object methodParameters, Boolean isInjected)
But I think it should return a cannot fake from mscorlib exception, not the cannot swap exception.