)
  }

  /**
   * The runner doesn't hold references to its queues! Otherwise we'd need a mechanism to clean them
   * up when they're no longer needed and that's annoying. Instead the task runner only tracks which
   * queues have work scheduled.
   */
  @Test fun activeQueuesContainsOnlyQueuesWithScheduledTasks() {
    redQueue.execute("task one", 100.µs) {
      // Do nothing.
    }