public void popItemTest()
        {
            ProgramStack stack = new ProgramStack();

            stack.PushItem(new StackItem(10));
            Assert.AreEqual(stack.PopItem(), 10);
        }
        public void pushItemTest()
        {
            ProgramStack stack = new ProgramStack();

            stack.PushItem(new StackItem(10));
            Assert.AreEqual(stack.StackItems.Count, 1);
        }