public void ContainsFlagEnumTest()
{
var week = WeekEnum.Monday;
FlagEnums.Contains(week, WeekEnum.Monday).ShouldBeTrue();
FlagEnums.Contains(week, WeekEnum.Tuesday).ShouldBeFalse();
FlagEnums.Add(ref week, WeekEnum.Tuesday, WeekEnum.Wednesday);
FlagEnums.Contains(week, WeekEnum.Monday).ShouldBeTrue();
FlagEnums.Contains(week, WeekEnum.Tuesday).ShouldBeTrue();
}