import java.util.LinkedList;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests for {@link Synchronized#deque} and {@link Queues#synchronizedDeque}.
 *
 * @author Kurt Alfred Kluever
 */
@NullUnmarked
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:
   *
   * {@snippet :
   * Deque<E> deque = Queues.synchronizedDeque(Queues.newArrayDeque());
   * ...
   * deque.add(element);  // Needn't be in synchronized block
   * ...
   * synchronized (deque) {  // Must synchronize on deque!