public void should_invoke_explicitly_implemented_method_by_original_interface() { var readOnlyStreamWithWriteExplicitlyImpl = new ReadOnlyStream(); var castedToInterface = (ITextStream) readOnlyStreamWithWriteExplicitlyImpl; castedToInterface.Write("Hehe"); var readResult = readOnlyStreamWithWriteExplicitlyImpl.Read(); // change the variable value to fix the test. const string expectedReadResult = ""; Assert.Equal(expectedReadResult, readResult); }