就像 Actors 对假人进行单元测试一样

Question

我是 Akka 和 Scala 的新手，我来自非并发世界。可能我做错了很多事情，即使与问题无关，我也会感谢反馈。

我正在用 Akka 和 Scala 做一个简单的聊天应用程序。我从 "typing feature" 开始（bc 业务需求）...这是 whatsapp 或 tellegram "John is typing a message" 中的典型功能。

我使用两种演员类型对其进行了建模：Talkers 和 Conversation，我想对我的 Conversation 演员进行单元测试。我的对话演员看起来像这样：

object Conversation {
  def props(conversationId: UUID, talkers: List[ActorRef])(out: ActorRef) = Props(new Conversation(conversationId, talkers))

  case class Typing(talkerId: TalkerId)
}

class Conversation(conversationId: UUID, talkers: List[ActorRef]) extends Actor with ActorLogging {
  def receive = LoggingReceive {
    case Typing(talkerId) =>
      // notify all talkers that a talker is typing
      // @TODO don't notify user which is typing
      talkers foreach {talker: ActorRef => talker ! InterlocutorTyping(talkerId)}
 }
}

我想，到现在已经很简单了。因此，在开始使用 Scala 和 Akka 编写代码之前，我已经进行了如下测试：

我得到了我的对话演员
我嘲笑说话的人
我向我的演员发送消息打字
我希望谈话者能得到通知

我真的不知道这在 Scala 和 Akka 中是否是正确的方法。我的测试（使用 scalatest）如下所示：

"Conversation" should {
"Notify interlocutors when a talker is typing" in {
  val talkerRef1 = system.actorOf(Props())
  val talkerRef2 = system.actorOf(Props())

  val talkerRef1Id = TalkerIdStub.random

  val conversationId = UUID.randomUUID()

  val conversationRef = system.actorOf(Props(classOf[Conversation], conversationId, List(talkerRef1, talkerRef2)))

  // should I use TestActorRef ?

  conversationRef ! InterlocutorTyping(talkerRef1Id)

  // assert that talker2 is notified when talker1 is typing
}
}

我应该使用 TestActorRef 吗？我应该使用 TestProbe() （我读到这是用于集成测试）
如何创建 Talker 模拟？这种做法正确吗？
向我的对话Actor注入List of Talkers是否正确？

我搜索了文档，但我认为有很多太旧了，我不确定代码示例是否仍然有效。

谢谢大家抽出时间，对于这个菜鸟问题深表歉意:=)

Answer 1

确实，Akka 的测试情况至少可以说有点混乱。

在 Akka 中通常有两种测试，同步和异步，有些人将其称为 'unit' 和 'integration' 测试。

'Unit tests' 是同步的，你直接测试接收方法而不需要演员系统等。在你的情况下，你会想要模拟 List[Talkers]，调用你的receive 方法并验证是否调用了发送方法。您可以直接使用 new Conversation(mockTalkers) 实例化您的 actor，在这种情况下没有必要使用 TestActorRef。对于模拟，我推荐 ScalaMock.
'Integration tests' 是异步的，通常测试多个 actor 一起工作。这是您继承 TestKit，实例化 TestProbes 作为您的谈话者，使用一个向 Conversation 演员发送消息，并验证另一个收到 InterlocutorTyping 消息.

您认为适合哪种测试取决于您。我个人的意见是，除非你的 actor 有复杂的内部行为，否则你应该跳过同步测试并直接进行异步 ('integration') 测试，因为这将涵盖你可能会错过的更棘手的并发边缘情况。这些也更 'black-box'，因此在您改进设计时对变化不那么敏感。

有关 doc page 的更多详细信息和代码示例。

Answer 2

最后我做到了（比问题多了一些功能）：

object Conversation {
  def props(conversationId: UUID)(out: ActorRef) = Props(new Conversation(conversationId))

  case class TalkerTyping(talkerId: TalkerId)
  case class TalkerStopTyping(talkerId: TalkerId)

  case class Join(talker: ActorRef)
  case class Leave(talker: ActorRef)
}

class Conversation(conversationId: UUID) extends Actor with ActorLogging {

  var talkers : ListBuffer[ActorRef] = ListBuffer.empty

  val senderFilter = { talker: ActorRef => talker != sender() }

  def receive = LoggingReceive {
    case Join =>
      talkers += sender()

    case Leave =>
      talkers -= sender()

    case TalkerTyping(talkerId) => // notify all talkers except sender that a talker is typing
      talkers filter senderFilter foreach { talker: ActorRef => talker ! InterlocutorTyping(talkerId) }

    case TalkerStopTyping(talkerId) => // notify all talkers except sender that a talker has stopped typing
      talkers filter senderFilter foreach { talker: ActorRef => talker ! InterlocutorStopTyping(talkerId) }
  }
}

我的测试：

class ConversationSpec extends ChatUnitTestCase("ConversationSpec") {

  trait ConversationTestHelper {
    val talker = TestProbe()
    val anotherTalker = TestProbe()
    val conversationRef = TestActorRef[Conversation](Props(new Conversation(UUID.randomUUID())))
    val conversationActor = conversationRef.underlyingActor
  }

  "Conversation" should {
    "let user join it" in new ConversationTestHelper {
      conversationActor.talkers should have size 0

      conversationRef ! Join

      conversationActor.talkers should have size 1
      conversationActor.talkers should contain(testActor)
    }
    "let joining user leave it" in new ConversationTestHelper {

      conversationActor.talkers should have size 0
      conversationRef ! Join
      conversationActor.talkers should have size 1
      conversationActor.talkers should contain(testActor)

      conversationRef ! Leave
      conversationActor.talkers should have size 0
      conversationActor.talkers should not contain testActor
    }
    "notify interlocutors when a talker is typing" in new ConversationTestHelper {

      val talker1 = TestProbe()
      val talker2 = TestProbe()

      talker1.send(conversationRef, Join)
      talker2.send(conversationRef, Join)

      val talker2Id = TalkerIdStub.random

      talker2.send(conversationRef, TalkerTyping(talker2Id))

      talker1.expectMsgPF() {
        case InterlocutorTyping(talkerIdWhoTyped) if talkerIdWhoTyped == talker2Id => true
      }
      talker2.expectNoMsg()
}
"notify interlocutors when a talker stop typing" in new ConversationTestHelper {

  val talker1 = TestProbe()
  val talker2 = TestProbe()

  talker1.send(conversationRef, Join)
  talker2.send(conversationRef, Join)

  val talker2Id = TalkerIdStub.random

  talker2.send(conversationRef, TalkerStopTyping(talker2Id))

  talker1.expectMsgPF() {
    case InterlocutorStopTyping(talkerIdWhoStopTyping) if talkerIdWhoStopTyping == talker2Id => true
  }
  talker2.expectNoMsg()
    }
  }
}

就像 Actors 对假人进行单元测试一样

Akka Actors unit testing for dummies

unit-testing

scala

akka

scalatest

akka-testkit