public void TestMultiplyTop2Exception()
        {
            StackOfInt SOI = new StackOfInt();

            SOI.Push(1);

            SOI.Multiplytop2();
        }
        public void TestMultiplyTop2()
        {
            StackOfInt SOI = new StackOfInt();

            SOI.Push(1);
            SOI.Push(11);
            SOI.Push(21);
            SOI.Multiplytop2();
            Assert.AreEqual(21 * 11, SOI.StackInt.Peek());
        }