delayedFlow akka streams

delayedFlow.scala

object TestRunner {
  def delayedFlow[T](delay: FiniteDuration)(implicit scheduler: Scheduler, ec: ExecutionContext): Flow[T, T, _] = {
    Flow[T].mapAsyncUnordered(Int.MaxValue) { out =>
      val promise = Promise[T]
      scheduler.scheduleOnce(delay)(promise.success(out))
      promise.future
    }
  }
}