WeakReference<Object> ref = new WeakReference<>(toBeGCed);
    final SettableFuture<@Nullable Void> settableFuture = SettableFuture.create();
    ListenableFuture<?> ignored =
        serializer.submitAsync(
            new AsyncCallable<@Nullable Void>() {
              @Override
              public ListenableFuture<@Nullable Void> call() {
                return settableFuture;
              }
            },
            directExecutor());

    SettableFuture<String> future = SettableFuture.create();
    SettableFuture<String> nested = SettableFuture.create();
    assertTrue(future.setFuture(nested));
    // Later attempts to set the future should return false.
    assertFalse(future.set("x"));
    assertFalse(future.setException(new Exception("bar")));
    assertFalse(future.setFuture(SettableFuture.<String>create()));

    assertEquals("foo", getChecked(immediateFuture("foo"), TwoArgConstructorException.class));
  }

  public void testGetCheckedUntimed_interrupted() {
    SettableFuture<String> future = SettableFuture.create();
    Thread.currentThread().interrupt();
    try {
      getChecked(future, TwoArgConstructorException.class);
      fail();
    } catch (TwoArgConstructorException expected) {

    unused = null; // Hint to the JIT that unused is unreachable
    GcFinalization.await(latch);
    assertEquals(0, latch.getCount());
  }

  public void testAwaitDone_future() {
    final SettableFuture<@Nullable Void> future = SettableFuture.create();
    Object unused =
        new Object() {
          @SuppressWarnings({"removal", "Finalize"}) // b/260137033
          @Override
          protected void finalize() {

    SettableFuture<String> future = SettableFuture.create();
    SettableFuture<String> nested = SettableFuture.create();
    assertTrue(future.setFuture(nested));
    // Later attempts to set the future should return false.
    assertFalse(future.set("x"));
    assertFalse(future.setException(new Exception("bar")));
    assertFalse(future.setFuture(SettableFuture.<String>create()));

  // together.  Now it should only be limited by available memory (and time)
  public void testSetFuture_stackOverflow() {
    SettableFuture<String> orig = SettableFuture.create();
    SettableFuture<String> prev = orig;
    for (int i = 0; i < 100000; i++) {
      SettableFuture<String> curr = SettableFuture.create();
      prev.setFuture(curr);
      prev = curr;
    }
    // prev represents the 'innermost' future

    WeakReference<Object> ref = new WeakReference<>(toBeGCed);
    final SettableFuture<@Nullable Void> settableFuture = SettableFuture.create();
    ListenableFuture<?> ignored =
        serializer.submitAsync(
            new AsyncCallable<@Nullable Void>() {
              @Override
              public ListenableFuture<@Nullable Void> call() {
                return settableFuture;
              }
            },
            directExecutor());

  public void testSameThreadSuccess() {
    SettableFuture<String> f = SettableFuture.create();
    MockCallback callback = new MockCallback("foo");
    addCallback(f, callback, directExecutor());
    f.set("foo");
  }

  public void testExecutorSuccess() {
    CountingSameThreadExecutor ex = new CountingSameThreadExecutor();
    SettableFuture<String> f = SettableFuture.create();
    MockCallback callback = new MockCallback("foo");

    unused = null; // Hint to the JIT that unused is unreachable
    GcFinalization.await(latch);
    assertEquals(0, latch.getCount());
  }

  public void testAwaitDone_future() {
    final SettableFuture<@Nullable Void> future = SettableFuture.create();
    Object unused =
        new Object() {
          @SuppressWarnings({"removal", "Finalize"}) // b/260137033
          @Override
          protected void finalize() {

  protected static final Exception EXCEPTION = new Exception("Test exception");

  protected SettableFuture<Integer> inputFuture;
  protected ListenableFuture<T> resultFuture;
  protected MockFutureListener listener;

  @Override
  protected void setUp() throws Exception {
    super.setUp();

    inputFuture = SettableFuture.create();
    resultFuture = buildChainingFuture(inputFuture);