assertThat(future.isDone()).isFalse();
    assertThat(executedRunnables).isEmpty();
    assertThat(pendingRunnables).hasSize(1);
    pendingRunnables.remove(0).run();
    assertThat(future.isDone()).isTrue();
    assertThat(executedRunnables).containsExactly(runnable);
    assertThat(pendingRunnables).isEmpty();
  }