public void WhenCollectionContainsValidIntProperty_ShouldCallTheToIntMethod(string intPropertyName) { //Arange int expectedInt = 5; IApiTypeConverter apiTypeConverterMock = MockRepository.GenerateMock <IApiTypeConverter>(); apiTypeConverterMock.Expect(x => x.ToInt(Arg <string> .Is.Anything)).IgnoreArguments().Return(expectedInt); IObjectConverter objectConverter = new Converters.ObjectConverter(apiTypeConverterMock); ICollection <KeyValuePair <string, string> > collection = new List <KeyValuePair <string, string> >() { new KeyValuePair <string, string>(intPropertyName, expectedInt.ToString()) }; //Act objectConverter.ToObject <SomeTestingObject>(collection); //Assert apiTypeConverterMock.VerifyAllExpectations(); }