public void ConstructorTest()
        {
            IBag <int> bag = new ResizingArrayBag <int>();

            Assert.IsTrue(bag.IsEmpty());
            Assert.AreEqual(0, bag.Size());
            Assert.IsTrue(string.IsNullOrWhiteSpace(bag.ToString()));
        }
        public void ToStringTest()
        {
            IBag <int> bag = new ResizingArrayBag <int>();

            for (int i = 0; i < 10; i++)
            {
                bag.Add(i);
            }
            Assert.AreEqual("0 1 2 3 4 5 6 7 8 9", bag.ToString());
        }