public void testInsertAfter() {

        String[] items = {"a","b","c","d","e","f"};
        ArrayList<DNode> list = createList(items);

        String[] testArray = {"a","b","z","c","d","e","f"};

        DNode head = list.get(0);
        DNode curr = list.get(1);
        DNode newNode = new DNode("z");

        head.insertAfter(curr, newNode);

        DNode temp = head;
        for (int i = 0; i < testArray.length-1; i++){
            assertEquals(testArray[i], temp.contents);
            temp = temp.next;
        }
        assertEquals(testArray[testArray.length-1], temp.contents);

        for (int i = testArray.length-1; i >= 0; i--){
            assertEquals(testArray[i], temp.contents);
            temp = temp.prev;
        }
    }