import java.util.Deque;
import java.util.Iterator;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Tests for {@link Synchronized#deque} and {@link Queues#synchronizedDeque}.
 *
 * @author Kurt Alfred Kluever
 */
public class SynchronizedDequeTest extends TestCase {

  protected Deque<String> create() {
    TestDeque<String> inner = new TestDeque<>();

   *
   * <p>It is imperative that the user manually synchronize on the returned deque when accessing any
   * of the deque's iterators:
   *
   * <pre>{@code
   * Deque<E> deque = Queues.synchronizedDeque(Queues.<E>newArrayDeque());
   * ...
   * deque.add(element);  // Needn't be in synchronized block
   * ...
   * synchronized (deque) {  // Must synchronize on deque!

   *
   * <p>It is imperative that the user manually synchronize on the returned deque when accessing any
   * of the deque's iterators:
   *
   * <pre>{@code
   * Deque<E> deque = Queues.synchronizedDeque(Queues.<E>newArrayDeque());
   * ...
   * deque.add(element);  // Needn't be in synchronized block
   * ...
   * synchronized (deque) {  // Must synchronize on deque!

  }

  static <E extends @Nullable Object> Deque<E> deque(Deque<E> deque, @CheckForNull Object mutex) {
    return new SynchronizedDeque<>(deque, mutex);
  }

  static final class SynchronizedDeque<E extends @Nullable Object> extends SynchronizedQueue<E>
      implements Deque<E> {

    SynchronizedDeque(Deque<E> delegate, @CheckForNull Object mutex) {
      super(delegate, mutex);
    }

    @Override

  }

  static <E extends @Nullable Object> Deque<E> deque(Deque<E> deque, @CheckForNull Object mutex) {
    return new SynchronizedDeque<>(deque, mutex);
  }

  static final class SynchronizedDeque<E extends @Nullable Object> extends SynchronizedQueue<E>
      implements Deque<E> {

    SynchronizedDeque(Deque<E> delegate, @CheckForNull Object mutex) {
      super(delegate, mutex);
    }

    @Override