public void WhenArgumentsIsEqual() { IModelRepository mock = MockRepository.GenerateMock <IModelRepository> (); var modelCreator = new ModelCreator(mock); var theModel = new AnotherModel() { FieldA = 1, FieldB = "Test" }; modelCreator.CreateModel(theModel); mock.AssertWasCalled(p => p.Add(Arg <AnotherModel> .Is.Equal(theModel))); }