public void ChangeByIndexTest(int[] array, int index, int value, int[] expArray)
{
DLinkedList expected = new DLinkedList(expArray);
DLinkedList actual = new DLinkedList(array);
actual.ChangeByIndex(index, value);
Assert.AreEqual(expected, actual);
}
public void ChangeByIndexNegative(int[] arr, int index, int value)
{
DLinkedList ll = new DLinkedList(arr);
Assert.Throws <IndexOutOfRangeException>(() => ll.ChangeByIndex(index, value));
}