public void Pushing_items_and_Popping_results_in_LIFO_action()
        {
            var stack = new MyStack();

            stack.Push("1");
            stack.Push("2");
            stack.Push("3");

            var result1 = stack.Pop();
            var result2 = stack.Pop();
            var result3 = stack.Pop();

            Assert.AreEqual("3", result1);
            Assert.AreEqual("2", result2);
            Assert.AreEqual("1", result3);
        }
        public void Popping_from_empty_stack_doesnt_throw_exception()
        {
            var stack  = new MyStack();
            var result = stack.Pop();

            Assert.IsNull(result);
        }
        public void Can_pop_items_off()
        {
            var stack = new MyStack();

            stack.Push("Foo");
            var result = stack.Pop();

            Assert.AreEqual("Foo", result);
        }