public void Front_ExceptionExpected()
        {
            //arrange
            QueueN <int> q = new QueueN <int>();

            //assert
            Assert.Throws(typeof(InvalidOperationException), () => q.Front());
        }
        public void PushFrontPop_intArray_RightOrderOfElementsExpected
            (int[] data)
        {
            //arrange
            QueueN <int> q = new QueueN <int>(2);

            //act
            for (int i = 0; i < data.Length; i++)
            {
                q.Push(data[i]);
            }
            //assert
            for (int i = 0; i < data.Length; i++)
            {
                int actual = q.Front();
                Assert.AreEqual(data[i], actual);
                q.Pop();
            }
            Assert.AreEqual(true, q.Empty, "queue is not empty, but should be");
        }