public void Item_count_works_on_add()
        {
            // setup
            var router = new FifoItemRouterWithCount <int>();

            // execute
            foreach (var r in Enumerable.Range(0, 10))
            {
                router.Route(r, 0);

                // verify
                router.Count().Should().Be(r + 1);
            }
        }
        public void Item_count_works_on_remove()
        {
            // setup
            var router = new FifoItemRouterWithCount <int>();

            foreach (var r in Enumerable.Range(0, 10))
            {
                router.Route(r, 0);
            }

            foreach (var r in Enumerable.Range(0, 10))
            {
                router.Remove(r);

                router.Count().Should().Be(10 - r - 1);
            }
        }