RateLimiter rateLimiter = new SmoothWarmingUp(stopwatch, warmupPeriod, unit, coldFactor);
    rateLimiter.setRate(permitsPerSecond);
    return rateLimiter;
  }

  /**
   * The underlying timer; used both to measure elapsed time and sleep as necessary. A separate
   * object to facilitate testing.
   */
  private final SleepingStopwatch stopwatch;

   * calling thread wait for that time.
   *
   * The simplest way to maintain a rate of QPS is to keep the timestamp of the last granted
   * request, and ensure that (1/QPS) seconds have elapsed since then. For example, for a rate of
   * QPS=5 (5 tokens per second), if we ensure that a request isn't granted earlier than 200ms after
   * the last one, then we achieve the intended rate. If a request comes and the last request was

          if ((hash1 & (1 << k)) == (hash2 & (1 << k))) {
            same[k] += 1;
          } else {
            diff[k] += 1;
          }
        }
      }
      // measure probability and assert it's within margin of error
      for (int j = 0; j < hashBits; j++) {
        double prob = (double) diff[j] / (double) (diff[j] + same[j]);
        Assert.assertEquals(0.50d, prob, epsilon);
      }

    Set<Feature<?>> features = Sets.<Feature<?>>newHashSet(ExampleBaseFeature.BASE_FEATURE_1);
    assertSame(features, FeatureUtil.addImpliedFeatures(features));
  }

  public void testAddImpliedFeatures_addsImpliedFeatures() throws Exception {
    Set<Feature<?>> features;

    features = Sets.<Feature<?>>newHashSet(ExampleDerivedFeature.DERIVED_FEATURE_1);

   * @return the implied set of features
   */
  public static Set<Feature<?>> impliedFeatures(Set<Feature<?>> features) {
    Set<Feature<?>> impliedSet = new LinkedHashSet<>();
    Queue<Feature<?>> queue = new ArrayDeque<>(features);
    while (!queue.isEmpty()) {
      Feature<?> feature = queue.remove();
      for (Feature<?> implied : feature.getImpliedFeatures()) {
        if (!features.contains(implied) && impliedSet.add(implied)) {

  }

  /**
   * Waits until the given future {@linkplain Future#isDone is done}, invoking the garbage collector
   * as necessary to try to ensure that this will happen.
   *
   * @throws RuntimeException if timed out or interrupted while waiting
   */
  @SuppressWarnings("removal") // b/260137033
  public static void awaitDone(Future<?> future) {

    }

    abstract Map<String, String> wrap(HashMap<String, String> map);
  }

  private static TestSuite wrappedHashMapTests(
      WrappedHashMapGenerator generator, String name, Feature<?>... features) {
    List<Feature<?>> featuresList = Lists.newArrayList(features);
    Collections.addAll(
        featuresList,
        MapFeature.GENERAL_PURPOSE,
        CollectionFeature.SUPPORTS_ITERATOR_REMOVE,

   * directly. Doing this for {@link com.google.common.net.PercentEscaper} more than doubled the
   * performance for unescaped strings (as measured by {@code CharEscapersBenchmark}).
   *
   * @param string the literal string to be escaped
   * @return the escaped form of {@code string}
   * @throws NullPointerException if {@code string} is null

            setException(failure);
          }
        };

    ExecutionException ee1 = getExpectingExecutionException(future);
    ExecutionException ee2 = getExpectingExecutionException(future);

    // Ensure we get a unique execution exception on each get
    assertNotSame(ee1, ee2);

    assertThat(ee1).hasCauseThat().isSameInstanceAs(failure);
    assertThat(ee2).hasCauseThat().isSameInstanceAs(failure);

    assertEquals(1, numCalls.get());
  }

  /*
   * Under Android, MyError propagates up and fails the test?
   *
   * TODO(b/218700094): Does this matter to prod users, or is it just a feature of our testing
   * environment? If the latter, maybe write a custom Executor that avoids failing the test when it
   * sees an Error?
   */
  @AndroidIncompatible
  public void testTaskThrowsError() throws Exception {