/** @throws Exception If failed. */
  public void testPoll() throws Exception {
    ConcurrentLinkedDeque8<Integer> deque = new ConcurrentLinkedDeque8<>();

    deque.add(1);
    deque.add(2);
    deque.add(3);

    assert !deque.isEmpty();

    checkSize(deque, 3);

    // Poll 1.
    assertEquals(Integer.valueOf(1), deque.poll());

    assert !deque.isEmpty();

    checkSize(deque, 2);

    // Poll 2.
    assertEquals(Integer.valueOf(2), deque.poll());

    assert !deque.isEmpty();

    checkSize(deque, 1);

    // Poll 3.
    assertEquals(Integer.valueOf(3), deque.poll());

    assert deque.isEmpty();

    checkSize(deque, 0);
  }
  public void testUnlinkWithIterator() {
    ConcurrentLinkedDeque8<Integer> q = new ConcurrentLinkedDeque8<>();

    q.add(1);
    Node<Integer> n2 = q.addx(2);
    Node<Integer> n3 = q.addx(3);
    Node<Integer> n4 = q.addx(4);
    Node<Integer> n5 = q.addx(5);
    q.add(6);

    Iterator<Integer> it = q.iterator();

    assertTrue(it.hasNext());
    assertEquals(1, it.next().intValue());

    assertTrue(it.hasNext());
    assertEquals(2, it.next().intValue());

    assertTrue(it.hasNext());
    assertEquals(3, it.next().intValue());

    q.unlinkx(n2);
    q.unlinkx(n3);
    q.unlinkx(n4);
    q.unlinkx(n5);

    assertTrue(it.hasNext());
    assertEquals(4, it.next().intValue());

    assertTrue(it.hasNext());
    assertEquals(6, it.next().intValue());
  }
  public void testUnlink() {
    ConcurrentLinkedDeque8<Integer> deque = new ConcurrentLinkedDeque8<>();

    Node<Integer> n1 = deque.addx(1);
    Node<Integer> n2 = deque.addx(2);
    Node<Integer> n3 = deque.addx(3);
    Node<Integer> n4 = deque.addx(4);
    Node<Integer> n5 = deque.addx(5);

    deque.unlinkx(n2);

    checkSize(deque, 4);

    // Double unlinkx() call.
    deque.unlinkx(n2);

    checkSize(deque, 4);

    Iterator<Integer> iter = deque.iterator();

    boolean hasNext = iter.hasNext();

    assert hasNext;

    Integer next = iter.next();

    assert next == 1;

    iter.remove();

    // Iterator should have set item to null.
    assert n1.item() == null;

    checkSize(deque, 3);

    // Double unlinkx() call.
    deque.unlinkx(n1);

    checkSize(deque, 3);

    deque.unlinkx(n3);
    deque.unlinkx(n4);
    deque.unlinkx(n5);

    checkSize(deque, 0);
  }
  public void testEmptyDeque() {
    ConcurrentLinkedDeque8<Integer> deque = new ConcurrentLinkedDeque8<>();

    assert deque.poll() == null;
    assert deque.pollFirst() == null;
    assert deque.pollLast() == null;

    assert deque.peek() == null;
    assert deque.peekFirst() == null;
    assert deque.peekLast() == null;

    checkSize(deque, 0);
  }
  /**
   * @param q Deque.
   * @param expSize Expected size.
   */
  @SuppressWarnings({"ForLoopReplaceableByForEach"})
  private <T> void checkSize(ConcurrentLinkedDeque8<T> q, int expSize) {
    int actualSize = 0;

    for (Iterator<T> iter = q.iterator(); iter.hasNext(); ) {
      iter.next();

      actualSize++;
    }

    assertEquals(expSize, actualSize);

    actualSize = 0;

    for (Iterator<T> iter = q.iterator(); iter.hasNext(); ) {
      iter.next();

      actualSize++;
    }

    assertEquals(expSize, actualSize);

    assertEquals(expSize, q.size());

    assertEquals(expSize, q.sizex());

    if (expSize > 0) {
      assert !q.isEmpty();

      assert !q.isEmptyx();
    } else {
      assert q.isEmpty();

      assert q.isEmptyx();
    }
  }
  public void testUnlinkLastWithIterator() {
    ConcurrentLinkedDeque8<Integer> q = new ConcurrentLinkedDeque8<>();

    q.add(1);
    q.addx(2);
    Node<Integer> n3 = q.addx(3);

    Iterator<Integer> it = q.iterator();

    assertTrue(it.hasNext());
    assertEquals(1, it.next().intValue());

    q.unlinkx(n3);

    assertTrue(it.hasNext());
    assertEquals(2, it.next().intValue());

    assertFalse(it.hasNext());
  }