if (state != State.NOT_DONE && (numListeners != 0 || numThreads != 0)) {
      throw new SkipThisScenarioException();
    }
  }

  // This exclusion doesn't exclude the TOMBSTONE objects we set. So 'done' NEW futures will look
  // larger than they are.
  @SuppressWarnings("FutureReturnValueIgnored")
  @Footprint(exclude = {Runnable.class, Executor.class, Thread.class, Exception.class})
  public Object measureSize() {

 * <p>Useful for testing the behavior of Future utilities against odd futures.
 *
 * @author Anthony Zana
 */
@GwtCompatible
@NullUnmarked
final class UncheckedThrowingFuture<V> extends AbstractFuture<V> {

  public static <V> ListenableFuture<V> throwingError(Error error) {
    UncheckedThrowingFuture<V> future = new UncheckedThrowingFuture<V>();
    future.complete(checkNotNull(error));
    return future;
  }

import java.util.concurrent.TimeoutException;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Unit tests for any listenable future that chains other listenable futures. Unit tests need only
 * override buildChainingFuture and getSuccessfulResult, but they can add custom tests as needed.
 *
 * @author Nishant Thakkar
 */
@NullUnmarked
@GwtIncompatible

 *       Future} is "completed" even if it is cancelled while its underlying work continues on a
 *       thread, an RPC, etc. The {@code Future} is also "completed" if it fails "early" -- for
 *       example, if the deadline expires on a {@code Future} returned from {@link
 *       Futures#withTimeout} while the {@code Future} it wraps continues its underlying work. So

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import org.jspecify.annotations.Nullable;

/** Implementation of {@link Futures#immediateFuture}. */
@GwtCompatible
// TODO(cpovirk): Make this final (but that may break Mockito spy calls).
class ImmediateFuture<V extends @Nullable Object> implements ListenableFuture<V> {

 */

package com.google.common.util.concurrent;

import static com.google.common.util.concurrent.Futures.immediateFailedFuture;

import com.google.common.annotations.GwtCompatible;
import java.util.concurrent.Future;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Classes and futures used in {@link FuturesGetCheckedTest} and {@link FuturesGetUncheckedTest}.
 */
@GwtCompatible

 */

package com.google.common.util.concurrent;

import static com.google.common.util.concurrent.Futures.immediateFailedFuture;

import com.google.common.annotations.GwtCompatible;
import java.util.concurrent.Future;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Classes and futures used in {@link FuturesGetCheckedTest} and {@link FuturesGetUncheckedTest}.
 */
@GwtCompatible

import java.util.concurrent.TimeoutException;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Unit tests for any listenable future that chains other listenable futures. Unit tests need only
 * override buildChainingFuture and getSuccessfulResult, but they can add custom tests as needed.
 *
 * @author Nishant Thakkar
 */
@NullUnmarked
@GwtIncompatible

                    errors.incrementAndGet();
                }
            }));
        }

        startLatch.countDown();
        for (final Future<?> future : futures) {
            future.get();
        }

        executor.shutdown();
        assertEquals(0, errors.get());
        engine.close();
    }

    /**

      throws InterruptedException, ExecutionException {

    List<Future<Long>> futures = Lists.newArrayListWithCapacity(threads);
    for (int i = 0; i < threads; i++) {
      futures.add(threadPool.submit(task));
    }
    long total = 0;
    for (Future<Long> future : futures) {
      total += future.get();
    }
    return total;
  }

  private long runAddSingleThread(int reps) {