public void AccessToIndexNegative(int case_of_arr, int index)
        {
            ArrayList arr = new ArrayList(ArrayMock(case_of_arr));

            try { arr.AccessToIndex(index); }
            catch { Assert.Pass(); }
            Assert.Fail();
        }
        public void AccessToIndex(int case_of_arr, int index, int expected)
        {
            ArrayList arr = new ArrayList(ArrayMock(case_of_arr));

            Assert.AreEqual(expected, arr.AccessToIndex(index));
        }