使用Akka TestProbe接收消息的顺序

Question

我们有一个演员,我们正在编写单元测试,作为测试的一部分,我们想断言某些消息按特定顺序发送给另一个演员.在我们的单元测试中,接收消息的actor由Akka表示,Akka TestProbe在创建时被注入到被测试的actor中.

断言消息被发送到测试探针是没有问题的,但是我们一直在努力设法断言它们是以正确的顺序发送的(我们在文档中找不到任何合适的方法) .我们是如何实现这一目标的？

下面是一个突出问题的最小实现.

履行

case class Message(message: String)
case class ForwardedMessage(message: String)

class ForwardingActor(forwardTo: ActorRef) extends Actor {
  def receive = {
    case Message(message) =>
      forwardTo ! ForwardedMessage(message)
  }
}

单元测试

class ForwardMessagesInOrderTest extends TestKit(ActorSystem("testSystem"))
                                 with WordSpecLike
                                 with MustMatchers {

  "A forwarding actor" must {
    val forwardingReceiver = TestProbe()
    val forwardingActor = system.actorOf(Props(new ForwardingActor(forwardingReceiver.ref)))

    "forward messages in the order they are received" in {
      forwardingActor ! Message("First message")
      forwardingActor ! Message("Second message")

      // This is the closest way we have found of achieving what we are looking for, it asserts
      // that both messages were received, but doesn't assert correct order. The test will pass
      // regardless which way round we put the messages below.
      forwardingReceiver.expectMsgAllOf(
          ForwardedMessage("Second message"),
          ForwardedMessage("First message"))
    }
  }
}

Answer 1

我将建议对您的测试规范进行两项更改.首先,在创建测试中的actor时,使用TestActorRef如下:

val forwardingActor = TestActorRef(new ForwardingActor(forwardingReceiver.ref))

使用a TestActorRef将确保CallingThreadDispatcher使用它,从测试异步代码(演员是)中删除任何复杂性.完成后,您可以将断言更改为:

forwardingReceiver.expectMsg(ForwardedMessage("First message"))
forwardingReceiver.expectMsg(ForwardedMessage("Second message"))

这些断言本质上是有序的,所以如果事情不按顺序排列,它们就会失败.这应该可以解决您的问题.