}
    }

    private static class RunnableExecutorPair {
      final Runnable runnable;
      final Executor executor;

      RunnableExecutorPair(Runnable runnable, Executor executor) {
        this.runnable = runnable;
        this.executor = executor;
      }

      void execute() {
        try {
          executor.execute(runnable);
        } catch (RuntimeException e) {

  }

  public void testToString() {
    Runnable[] currentTask = new Runnable[1];
    Executor delegate =
        new Executor() {
          @Override
          public void execute(Runnable task) {
            currentTask[0] = task;
            task.run();
            currentTask[0] = null;
          }

          @Override
          public String toString() {

  }

  private static class ForwardingRunnable implements Runnable {

    private final Runnable runnable;

    ForwardingRunnable(Runnable runnable) {
      this.runnable = runnable;
    }

    @Override
    public void run() {
      runnable.run();
    }

    @Override
    public String toString() {
      return runnable.toString();
    }
  }

  private interface Adder {

      }
    }

    private static class RunnableExecutorPair {
      final Runnable runnable;
      final Executor executor;

      RunnableExecutorPair(Runnable runnable, Executor executor) {
        this.runnable = runnable;
        this.executor = executor;
      }

      void execute() {
        try {
          executor.execute(runnable);
        } catch (RuntimeException e) {

  enum WorkerRunningState {
    /** Runnable is not running and not queued for execution */
    IDLE,
    /** Runnable is not running, but is being queued for execution */
    QUEUING,
    /** runnable has been submitted but has not yet begun execution */
    QUEUED,
    RUNNING,
  }

  /** Underlying executor that all submitted Runnable objects are run on. */
  private final Executor executor;

    }

    @Override
    public T call() throws Exception {
      return delegate.call();
    }
  }

  private static final class WrappedRunnable implements Runnable {
    private final Runnable delegate;

    WrappedRunnable(Runnable delegate) {
      this.delegate = delegate;
    }

    @Override
    public void run() {
      delegate.run();
    }
  }

  }

  public void testToString() {
    Runnable[] currentTask = new Runnable[1];
    Executor delegate =
        new Executor() {
          @Override
          public void execute(Runnable task) {
            currentTask[0] = task;
            task.run();
            currentTask[0] = null;
          }

          @Override
          public String toString() {

// instead of using an AtomicReferenceFieldUpdater. This reference stores Thread instances
// and DONE/INTERRUPTED - they have a common ancestor of Runnable.
abstract class InterruptibleTask<T extends @Nullable Object>
    extends AtomicReference<@Nullable Runnable> implements Runnable {
  static {
    // Prevent rare disastrous classloading in first call to LockSupport.park.
    // See: https://bugs.openjdk.org/browse/JDK-8074773

  }

  private static class ForwardingRunnable implements Runnable {

    private final Runnable runnable;

    ForwardingRunnable(Runnable runnable) {
      this.runnable = runnable;
    }

    @Override
    public void run() {
      runnable.run();
    }

    @Override
    public String toString() {
      return runnable.toString();
    }
  }

  private interface Adder {

  }

  @CanIgnoreReturnValue
  public B withSetUp(Runnable setUp) {
    this.setUp = setUp;
    return self();
  }

  public Runnable getSetUp() {
    return setUp;
  }

  @CanIgnoreReturnValue
  public B withTearDown(Runnable tearDown) {
    this.tearDown = tearDown;
    return self();
  }

  public Runnable getTearDown() {
    return tearDown;
  }

  // Features