public void RemoveHourShouldByEqualsTrue() { //Output 04/03/2010 16:02 datetime = DateTime.Parse("04/03/2010 17:00"); string microsoft_result = datetime.AddHours(-2).ToString("dd/MM/yyyy HH:mm"); string new_datetime = my_datetime.SubtractHours("04/03/2010 17:00", 2); string my_result = my_datetime.Format(new_datetime, 1); Assert.AreEqual(microsoft_result, my_result); }