redQueue.execute("task") {
      log += "run@${taskFaker.nanoTime}"
    }

    val idleLatch1 = redQueue.idleLatch()
    val idleLatch2 = redQueue.idleLatch()
    assertThat(idleLatch2).isSameInstanceAs(idleLatch1)
  }

  @Test fun cancelAllWhenEmptyDoesNotStartWorkerThread() {
    redQueue.execute("red task", 100.µs) {
      error("expected to be canceled")
    }

    readerToClose?.closeQuietly()
  }

  /** For testing: force this web socket to release its threads. */
  @Throws(InterruptedException::class)
  fun tearDown() {
    taskQueue.shutdown()
    taskQueue.idleLatch().await(10, TimeUnit.SECONDS)
  }

  @Synchronized fun sentPingCount(): Int = sentPingCount

  @Synchronized fun receivedPingCount(): Int = receivedPingCount

    // Cause acceptConnections() to break out.
    serverSocket.closeQuietly()

    // Await shutdown.
    for (queue in taskRunner.activeQueues()) {
      if (!queue.idleLatch().await(5, TimeUnit.SECONDS)) {
        throw AssertionError("Gave up waiting for queue to shut down")
      }
    }
    taskRunnerBackend.shutdown()
  }

  private fun serveConnection(