}
    }

    override fun <T> decorate(queue: BlockingQueue<T>) = queue

    override fun execute(
      taskRunner: TaskRunner,
      runnable: Runnable,
    ) {
      executor.execute(runnable)
    }

    fun shutdown() {
      executor.shutdown()
    }
  }

  companion object {
    val logger: Logger = Logger.getLogger(TaskRunner::class.java.name)

  /** Guarded by [TaskRunner.lock]. */
  private var activeThreads = 0

  /** A task runner that posts tasks to this fake. Tasks won't be executed until requested. */
  val taskRunner: TaskRunner =
    TaskRunner(
      object : TaskRunner.Backend {
        override fun execute(
          taskRunner: TaskRunner,
          runnable: Runnable,
        ) {
          taskRunner.assertThreadHoldsLock()

  @Test fun singleQueueIsSerial() {
    redQueue.execute("task one", 100.µs) {
      log += "one:run@${taskFaker.nanoTime} parallel=${taskFaker.isParallel}"
    }

    redQueue.execute("task two", 100.µs) {
      log += "two:run@${taskFaker.nanoTime} parallel=${taskFaker.isParallel}"
    }

    redQueue.execute("task three", 100.µs) {