public void Should_have_error_Previous_Value(DirectionType directionType) { DirectionType prevDirectionType = directionType.PreviousValue(); DirectionType correctDirectionType = DirectionTypeList[(DirectionTypeList.IndexOf(directionType) - 1 + DirectionTypeList.Count()) % DirectionTypeList.Count()]; Assert.AreEqual(correctDirectionType, prevDirectionType); }