问题 Suppose, that I've got a following class: public abstract class Test { internal abstract int Prop { get; } } Now, I try to make a mock using NSubstitute: var mock = Substitute.For<Test>(); But that fails: Method 'get_Prop' in type 'Castle.Proxies.TestProxy' from assembly 'DynamicProxyGenAssembly2, Version=0.0.0.0, Culture=neutral, PublicKeyToken=a621a9e7e5c32e69' does not have an implementation. I thought of adding NSubstitute to [InternalsVisibleTo] , but unfortunately my tested assembly is