public void AddTest()
{
SchoolDay schoolDay = new SchoolDay();
int count = schoolDay.Count;
DateTime end = schoolDay.End;
ShortBreak shortBreak = new ShortBreak(schoolDay.Start);
schoolDay.Add(shortBreak);
Assert.Equal <int>(schoolDay.Count, count + 1);
Assert.Equal(schoolDay.Last, shortBreak);
Assert.Equal <DateTime>(schoolDay.End, end.Add(shortBreak.Duration));
Assert.Equal <DateTime>(shortBreak.Start, end);
Assert.Equal(shortBreak.End, schoolDay.End);
Assert.Equal <TimeSpan>(shortBreak.Duration, ShortBreak.ShortBreakDuration);
} // AddTest
