backend.shutdown()
  }

  @Test fun test() {
    val t1 = System.nanoTime() / 1e6

    val delays = mutableListOf(TimeUnit.MILLISECONDS.toNanos(1000), -1L)
    queue.schedule("task", TimeUnit.MILLISECONDS.toNanos(750)) {
      log.put("runOnce delays.size=${delays.size}")
      return@schedule delays.removeAt(0)
    }

    assertThat(log.take()).isEqualTo("runOnce delays.size=2")
    val t2 = System.nanoTime() / 1e6 - t1