firstCallable = new TestCallable(firstFuture);
  }

  @Override
  public void tearDown() throws Exception {
    executor.shutdown();
  }

  public void testCallableStartsAfterFirstFutureCompletes() {
    @SuppressWarnings({"unused", "nullness"})
    Future<?> possiblyIgnoredError = serializer.submitAsync(firstCallable, directExecutor());