assertTrue(future.isCancelled());
  }

  public void testAwaitClear() {
    WeakReference<Object> ref = createWeakReference();
    GcFinalization.awaitClear(ref);
    assertThat(ref.get()).isNull();
  }

  private WeakReference<Object> createWeakReference() {
    return new WeakReference<>(new Object());
  }

  public void testAwaitDone_finalizationPredicate() {

    assertTrue(future.isCancelled());
  }

  public void testAwaitClear() {
    WeakReference<Object> ref = createWeakReference();
    GcFinalization.awaitClear(ref);
    assertThat(ref.get()).isNull();
  }

  private WeakReference<Object> createWeakReference() {
    return new WeakReference<>(new Object());
  }

  public void testAwaitDone_finalizationPredicate() {

    AtomicReference<Object> sepStopwatchA =
        new AtomicReference<Object>(sepStopwatchC.getMethod("createUnstarted").invoke(null));
    AtomicReference<WeakReference<?>> sepStopwatchRef =
        new AtomicReference<WeakReference<?>>(
            (WeakReference<?>) sepFwrCons.newInstance(sepStopwatchA.get(), sepFrqA.get()));
    assertThat(sepStopwatchA.get()).isNotNull();

  public void testGetIfPresent_doesNotPreventClassUnloading() throws Exception {
    WeakReference<?> shadowLoaderReference = doTestClassUnloading();
    GcFinalization.awaitClear(shadowLoaderReference);
  }

  // Create a second ClassLoader and use it to get a second version of the TestEnum class.
  // Run Enums.getIfPresent on that other TestEnum and then return a WeakReference containing the

 * leaks, by ensuring that objects are no longer strongly referenced:
 *
 * {@snippet :
 * // Helper function keeps victim stack-unreachable.
 * private WeakReference<Foo> fooWeakRef() {
 *   Foo x = ....;
 *   WeakReference<Foo> weakRef = new WeakReference<>(x);
 *   // ... use x ...
 *   x = null; // Hint to the JIT that x is stack-unreachable
 *   return weakRef;
 * }
 * public void testFooLeak() {

  }

  private WeakReference<ClosingFuture<String>> leakClosingFuture(TestCloseable closeable) {
    ClosingFuture<String> willCloseCloseable =
        ClosingFuture.submit(
            closer -> {
              closer.eventuallyClose(closeable, directExecutor());
              return "";
            },
            directExecutor());
    return new WeakReference<>(willCloseCloseable);
  }

  }

  private WeakReference<ClosingFuture<String>> leakClosingFuture(TestCloseable closeable) {
    ClosingFuture<String> willCloseCloseable =
        ClosingFuture.submit(
            closer -> {
              closer.eventuallyClose(closeable, directExecutor());
              return "";
            },
            directExecutor());
    return new WeakReference<>(willCloseCloseable);
  }

 * leaks, by ensuring that objects are no longer strongly referenced:
 *
 * {@snippet :
 * // Helper function keeps victim stack-unreachable.
 * private WeakReference<Foo> fooWeakRef() {
 *   Foo x = ....;
 *   WeakReference<Foo> weakRef = new WeakReference<>(x);
 *   // ... use x ...
 *   x = null; // Hint to the JIT that x is stack-unreachable
 *   return weakRef;
 * }
 * public void testFooLeak() {

            return new Object();
          }
        };
    WeakReference<Object> ref = doNextAndGetWeakReference(itr);
    GcFinalization.awaitClear(ref);
  }

  @GwtIncompatible // weak references
  private WeakReference<Object> doNextAndGetWeakReference(Iterator<Object> itr) {
    return new WeakReference<>(itr.next());
  }

  public void testReentrantHasNext() {
    Iterator<Integer> iter =

            return new Object();
          }
        };
    WeakReference<Object> ref = doNextAndGetWeakReference(itr);
    GcFinalization.awaitClear(ref);
  }

  @GwtIncompatible // weak references
  private WeakReference<Object> doNextAndGetWeakReference(Iterator<Object> itr) {
    return new WeakReference<>(itr.next());
  }

  public void testReentrantHasNext() {
    Iterator<Integer> iter =