public void QuarterMonths()
        {
            var def = new DefaultDateTimeCalendarExtensions();

            Assert.Contains(1, def.QuarterMonths);
            Assert.Contains(4, def.QuarterMonths);
            Assert.Contains(7, def.QuarterMonths);
            Assert.Contains(10, def.QuarterMonths);
        }
 public void WeekEndsOn()
 {
     var def = new DefaultDateTimeCalendarExtensions();
     Assert.Equal(DayOfWeek.Sunday, def.WeekEndsOn);
 }