@Test
 public void testClone() throws ValueException {
   DoubleLinkedList dll = new DoubleLinkedList();
   dll.pushBack(6);
   dll.pushBack(5);
   DoubleLinkedList dll2 = dll.clone();
   assertEquals(true, dll.equals(dll2));
 }
  @Test
  public void testEqualsFalse() throws ValueException {

    DoubleLinkedList dll = new DoubleLinkedList();
    dll.pushBack(6);
    dll.pushBack(5);
    DoubleLinkedList dll2 = new DoubleLinkedList();
    dll2.pushFront(6);
    dll2.pushFront(5);
    assertEquals(false, dll.equals(dll2));
  }
  // no Exception expected
  @Test
  public void testEqualsNoException() throws ValueException {

    DoubleLinkedList dll = new DoubleLinkedList();
    dll.pushBack(6);
    dll.pushBack(5);
    DoubleLinkedList dll2 = new DoubleLinkedList();
    dll2.pushFront(6);
    dll2.pushFront(5);
    try {
      assertEquals(false, dll.equals(dll2));
    } catch (NullPointerException ex) {
      fail("No Exception expected!");
    }
  }