*
   * @since 12.0
   */
  public static <E> ArrayDeque<E> newArrayDeque() {
    return new ArrayDeque<>();
  }

  /**
   * Creates an {@code ArrayDeque} containing the elements of the specified iterable, in the order
   * they are returned by the iterable's iterator.
   *
   * @since 12.0
   */
  public static <E> ArrayDeque<E> newArrayDeque(Iterable<? extends E> elements) {
    if (elements instanceof Collection) {

 * Tests {@link SequentialExecutor}.
 *
 * @author JJ Furman
 */
public class SequentialExecutorTest extends TestCase {

  private static class FakeExecutor implements Executor {
    Queue<Runnable> tasks = Queues.newArrayDeque();

    @Override
    public void execute(Runnable command) {
      tasks.add(command);
    }

    boolean hasNext() {
      return !tasks.isEmpty();
    }

    void runNext() {

 * Tests {@link SequentialExecutor}.
 *
 * @author JJ Furman
 */
public class SequentialExecutorTest extends TestCase {

  private static class FakeExecutor implements Executor {
    Queue<Runnable> tasks = Queues.newArrayDeque();

    @Override
    public void execute(Runnable command) {
      tasks.add(command);
    }

    boolean hasNext() {
      return !tasks.isEmpty();
    }

    void runNext() {

    final L listener;
    final Executor executor;

    @GuardedBy("this")
    final Queue<ListenerCallQueue.Event<L>> waitQueue = Queues.newArrayDeque();

    @GuardedBy("this")
    final Queue<Object> labelQueue = Queues.newArrayDeque();

    @GuardedBy("this")
    boolean isThreadScheduled;

    PerListenerQueue(L listener, Executor executor) {
      this.listener = checkNotNull(listener);

    private final ThreadLocal<Queue<Event>> queue =
        new ThreadLocal<Queue<Event>>() {
          @Override
          protected Queue<Event> initialValue() {
            return Queues.newArrayDeque();
          }
        };

    /** Per-thread dispatch state, used to avoid reentrant event dispatching. */
    private final ThreadLocal<Boolean> dispatching =
        new ThreadLocal<Boolean>() {