assertThrows(IllegalArgumentException.class, () -> multiset.add(KEY, COUNT_TO_ADD));
  }

  /**
   * Simulate some of the races that can happen on add. We can't easily simulate the race that
   * happens when an {@link AtomicInteger#compareAndSet} fails, but we can simulate the case where
   * the putIfAbsent returns a non-null value, and the case where the replace() of an observed zero
   * fails.
   */

    assertThrows(IllegalArgumentException.class, () -> multiset.add(KEY, COUNT_TO_ADD));
  }

  /**
   * Simulate some of the races that can happen on add. We can't easily simulate the race that
   * happens when an {@link AtomicInteger#compareAndSet} fails, but we can simulate the case where
   * the putIfAbsent returns a non-null value, and the case where the replace() of an observed zero
   * fails.
   */

 *
 * @author mike nonemacher
 */
@SuppressWarnings("GuardedBy") // TODO(b/35466881): Fix or suppress.
class CacheTesting {

  /**
   * Poke into the Cache internals to simulate garbage collection of the value associated with the
   * given key. This assumes that the associated entry is a WeakValueReference or a
   * SoftValueReference (and not a LoadingValueReference), and throws an IllegalStateException if

              new CountDownLatch(1).await(); // the interrupt will wake us up
            } catch (InterruptedException ie) {
              // continue
            }
            LockSupport.unpark(Thread.currentThread()); // simulate a spurious wakeup.
            return null;
          }

          @Override
          boolean isDone() {
            return false;
          }

          @Override

 *
 * @author mike nonemacher
 */
@SuppressWarnings("GuardedBy") // TODO(b/35466881): Fix or suppress.
class CacheTesting {

  /**
   * Poke into the Cache internals to simulate garbage collection of the value associated with the
   * given key. This assumes that the associated entry is a WeakValueReference or a
   * SoftValueReference (and not a LoadingValueReference), and throws an IllegalStateException if

              new CountDownLatch(1).await(); // the interrupt will wake us up
            } catch (InterruptedException ie) {
              // continue
            }
            LockSupport.unpark(Thread.currentThread()); // simulate a spurious wakeup.
            return null;
          }

          @Override
          boolean isDone() {
            return false;
          }

          @Override

 * that is already in the desired state.
 *
 * <p>When testing code that uses this class, use {@link #createUnstarted(Ticker)} or {@link
 * #createStarted(Ticker)} to supply a fake or mock ticker. This allows you to simulate any valid
 * behavior of the stopwatch.
 *
 * <p><b>Note:</b> This class is not thread-safe.
 *
 * <p><b>Warning for Android users:</b> a stopwatch with default behavior may not continue to keep

 * that is already in the desired state.
 *
 * <p>When testing code that uses this class, use {@link #createUnstarted(Ticker)} or {@link
 * #createStarted(Ticker)} to supply a fake or mock ticker. This allows you to simulate any valid
 * behavior of the stopwatch.
 *
 * <p><b>Note:</b> This class is not thread-safe.
 *
 * <p><b>Warning for Android users:</b> a stopwatch with default behavior may not continue to keep

   * Assigns a thread to the given {@link Future} to provide {@link ListenableFuture} functionality.
   *
   * <p><b>Warning:</b> If the input future does not already implement {@code ListenableFuture}, the
   * returned future will emulate {@link ListenableFuture#addListener} by taking a thread from an
   * internal, unbounded pool at the first call to {@code addListener} and holding it until the
   * future is {@linkplain Future#isDone() done}.
   *

        assertTrue(greater + ".compareTo(" + t + ')', greater.compareTo(t) > 0);
        assertFalse(greater.equals(t));
      }
    }
  }

  /**
   * Returns a collection that simulates concurrent modification by having its size method return
   * incorrect values. This is useful for testing methods that must treat the return value from
   * size() as a hint only.
   *