public void TimeSpanExtSecondTest_subtraction_operator()
        {
            DateTime dt = new DateTime(2000, 1, 1, 1, 1, 33, 333);
              Decimal value = 3693.333M;
              TimeSpanExtSecond edt = new TimeSpanExtSecond(value);
              DateTime expected = new DateTime(2000, 1, 1);

              DateTime actual;
              actual = dt - edt;

              Assert.AreEqual(expected, actual);
        }
        public void Subtraction_from_TimeSpanExtBase_returns_a_valid_TimeSpanExtBase()
        {
            DateTime dt = new DateTime(2000, 1, 1);
              TimeSpanExtSecond edt = new TimeSpanExtSecond(3);
              TimeSpanExtSecond edt2 = new TimeSpanExtSecond(2);
              DateTime expected = new DateTime(2000, 1, 1, 0, 0, 1);

              TimeSpanExt composite = edt - edt2;
              DateTime actual;
              actual = dt + composite;

              Assert.AreEqual(expected, actual);
        }