public void ShallBuildCalendarDays()
{
List <CalendarDay> calendarDays = calendarController.BuildMonthCalendarDays(2020, 6);
Assert.That(calendarDays.Count(), Is.EqualTo(CalendarController.COUNT_DAYS_IN_CALENDAR)); //refactor to use the const
Assert.That(calendarDays.First().DayNumber, Is.EqualTo(31));
Assert.That(calendarDays.First().IsEmpty);
Assert.That(calendarDays.ElementAt(30).IsEmpty, Is.EqualTo(false));
Assert.That(calendarDays.ElementAt(30).DayNumber, Is.EqualTo(30));
Assert.That(calendarDays.ElementAt(31).DayNumber, Is.EqualTo(1));
Assert.That(calendarDays.ElementAt(31).IsEmpty);
}