public void WhenCalendarHasANonWorkingDayOfWeekReturnsNonWorkingForThatDayOfWeekAndFalseForAnotherOne()
{
WorkingDatesCalendar argentineCalendar = new WorkingDatesCalendar();
argentineCalendar.AddNonWorkingDayOfWeek(DayOfWeek.Sunday);
Assert.IsFalse(argentineCalendar.IsNonWorkingDate(someSaturday()));
Assert.IsTrue(argentineCalendar.IsNonWorkingDate(someSunday()));
}