scala - 测试将 Stash 与 TestActorRef 混合的 Akka actor

Question

我遇到了一个扩展 Stash 的 actor 的问题，并且在一个简单的 ActorSystem 中使用 actorOf 实例化它时效果很好。现在我实际上想在我的程序中使用它们之前为我的 stashing actor 编写一些测试。但是我想不出在我的测试套件中使用 TestActorRef 与这个 actor 的方法。

有效的代码如下所示:

import akka.actor.{Stash, Actor, ActorSystem, Props}
import com.typesafe.config.ConfigFactory

object StashTest {
  val config = ConfigFactory.parseString(
    """
      |akka.actor.default-mailbox {
      | mailbox-type = "akka.dispatch.UnboundedDequeBasedMailbox"
      |}
    """.stripMargin)
}

class StashTestActor extends Stash {

  def receive: Actor.Receive = {
    case "unstash" =>
      unstashAll()
      context become print
    case msg => stash()
  }

  def print: Actor.Receive = {
    case msg => println(s"Unstashed message: $msg")
  }
}

val system = ActorSystem("stashSystem", StashTest.config)
val ref = system.actorOf(Props[StashTestActor])

ref ! "stash me"
ref ! "blah"
ref ! "unstash"

哪个打印

Unstashed message: stash me

Unstashed message: blah

但是，如果我尝试为这个 Actor 编写 WordSpec 测试，它会给我留下一些令人讨厌的异常(exception)，我无法弄清楚他们希望我在我的代码中更改什么。

测试类看起来像这样

import akka.testkit.{TestActorRef, TestKit}
import akka.actor.{Stash, Actor, ActorSystem}
import org.scalatest.{WordSpecLike, MustMatchers}
import com.typesafe.config.ConfigFactory


class StashTestActor extends Stash {

  def receive: Actor.Receive = {
    case "unstash" =>
      unstashAll()
      context become print
    case msg => stash()
  }

  def print: Actor.Receive = {
    case msg => println(s"Unstashed message: $msg")
  }
}


class StashTest extends TestKit(ActorSystem("testSystem", StashTest.config))
with WordSpecLike
with MustMatchers {

  "A simple stashing actor" must {
    val actorRef = TestActorRef[StashTestActor]

    "stash messages" in {
      actorRef ! "stash me!"
    }

    "unstash all messages" in {
      actorRef ! "unstash"
    }
  }
}

object StashTest {
  val config = ConfigFactory.parseString(
    """
      |akka.actor.default-mailbox {
      | mailbox-type = "akka.dispatch.UnboundedDequeBasedMailbox"
      |}
    """.stripMargin)
}

运行测试时，我得到以下在 TestActorRef 实例化期间抛出的异常。

[ERROR] [08/20/2013 14:19:40.765] [testSystem-akka.actor.default-dispatcher-3] [akka://testSystem/user/$$a] Could not instantiate Actor
Make sure Actor is NOT defined inside a class/trait,
if so put it outside the class/trait, f.e. in a companion object,
OR try to change: 'actorOf(Props[MyActor]' to 'actorOf(Props(new MyActor)'.
akka.actor.ActorInitializationException: exception during creation
    at akka.actor.ActorInitializationException$.apply(Actor.scala:218)
    at akka.actor.ActorCell.create(ActorCell.scala:578)
    at akka.actor.ActorCell.invokeAll$1(ActorCell.scala:425)
    at akka.actor.ActorCell.systemInvoke(ActorCell.scala:447)
    at akka.dispatch.Mailbox.processAllSystemMessages(Mailbox.scala:262)
    at akka.testkit.CallingThreadDispatcher.process$1(CallingThreadDispatcher.scala:244)
    at akka.testkit.CallingThreadDispatcher.runQueue(CallingThreadDispatcher.scala:284)
    at akka.testkit.CallingThreadDispatcher.register(CallingThreadDispatcher.scala:153)
    at akka.dispatch.MessageDispatcher.attach(AbstractDispatcher.scala:133)
    at akka.actor.dungeon.Dispatch$class.start(Dispatch.scala:84)
    at akka.actor.ActorCell.start(ActorCell.scala:338)
    at akka.testkit.TestActorRef.<init>(TestActorRef.scala:50)
    at akka.testkit.TestActorRef$.apply(TestActorRef.scala:141)
    at akka.testkit.TestActorRef$.apply(TestActorRef.scala:137)
    at akka.testkit.TestActorRef$.apply(TestActorRef.scala:146)
    at akka.testkit.TestActorRef$.apply(TestActorRef.scala:144)
    at stashActorTest.StashTest$$anonfun$1.apply$mcV$sp(StashTestActor.scala:29)
    at stashActorTest.StashTest$$anonfun$1.apply(StashTestActor.scala:28)
    at stashActorTest.StashTest$$anonfun$1.apply(StashTestActor.scala:28)
    at org.scalatest.SuperEngine.registerNestedBranch(Engine.scala:613)
    at org.scalatest.WordSpecLike$class.org$scalatest$WordSpecLike$$registerBranch(WordSpecLike.scala:120)
    at org.scalatest.WordSpecLike$$anon$2.apply(WordSpecLike.scala:851)
    at org.scalatest.words.MustVerb$StringMustWrapperForVerb$class.must(MustVerb.scala:189)
    at org.scalatest.matchers.MustMatchers$StringMustWrapper.must(MustMatchers.scala:6167)
    at stashActorTest.StashTest.<init>(StashTestActor.scala:28)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
    at java.lang.Class.newInstance(Class.java:374)
    at org.scalatest.tools.Framework$ScalaTestTask.execute(Framework.scala:444)
    at sbt.TestRunner.runTest$1(TestFramework.scala:84)
    at sbt.TestRunner.run(TestFramework.scala:94)
    at sbt.TestFramework$$anon$2$$anonfun$$init$$1$$anonfun$apply$8.apply(TestFramework.scala:224)
    at sbt.TestFramework$$anon$2$$anonfun$$init$$1$$anonfun$apply$8.apply(TestFramework.scala:224)
    at sbt.TestFramework$.sbt$TestFramework$$withContextLoader(TestFramework.scala:212)
    at sbt.TestFramework$$anon$2$$anonfun$$init$$1.apply(TestFramework.scala:224)
    at sbt.TestFramework$$anon$2$$anonfun$$init$$1.apply(TestFramework.scala:224)
    at sbt.TestFunction.apply(TestFramework.scala:229)
    at sbt.Tests$$anonfun$7.apply(Tests.scala:196)
    at sbt.Tests$$anonfun$7.apply(Tests.scala:196)
    at sbt.std.Transform$$anon$3$$anonfun$apply$2.apply(System.scala:45)
    at sbt.std.Transform$$anon$3$$anonfun$apply$2.apply(System.scala:45)
    at sbt.std.Transform$$anon$4.work(System.scala:64)
    at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:237)
    at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:237)
    at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:18)
    at sbt.Execute.work(Execute.scala:244)
    at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:237)
    at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:237)
    at sbt.ConcurrentRestrictions$$anon$4$$anonfun$1.apply(ConcurrentRestrictions.scala:160)
    at sbt.CompletionService$$anon$2.call(CompletionService.scala:30)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
    at java.util.concurrent.FutureTask.run(FutureTask.java:166)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
    at java.util.concurrent.FutureTask.run(FutureTask.java:166)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:724)
Caused by: akka.actor.ActorInitializationException: Could not instantiate Actor
Make sure Actor is NOT defined inside a class/trait,
if so put it outside the class/trait, f.e. in a companion object,
OR try to change: 'actorOf(Props[MyActor]' to 'actorOf(Props(new MyActor)'.
    at akka.actor.ActorInitializationException$.apply(Actor.scala:218)
    at akka.testkit.TestActorRef$$anonfun$apply$2$$anonfun$apply$1.applyOrElse(TestActorRef.scala:148)
    at akka.testkit.TestActorRef$$anonfun$apply$2$$anonfun$apply$1.applyOrElse(TestActorRef.scala:147)
    at scala.runtime.AbstractPartialFunction.apply(AbstractPartialFunction.scala:33)
    at scala.util.Failure$$anonfun$recover$1.apply(Try.scala:185)
    at scala.util.Try$.apply(Try.scala:161)
    at scala.util.Failure.recover(Try.scala:185)
    at akka.testkit.TestActorRef$$anonfun$apply$2.apply(TestActorRef.scala:147)
    at akka.testkit.TestActorRef$$anonfun$apply$2.apply(TestActorRef.scala:153)
    at akka.actor.CreatorFunctionConsumer.produce(Props.scala:369)
    at akka.actor.Props.newActor(Props.scala:323)
    at akka.actor.ActorCell.newActor(ActorCell.scala:534)
    at akka.actor.ActorCell.create(ActorCell.scala:560)
    ... 58 more
Caused by: java.lang.NullPointerException
    at akka.actor.UnrestrictedStash$class.$init$(Stash.scala:82)
    at stashActorTest.StashTestActor.<init>(StashTestActor.scala:9)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
    at akka.actor.ReflectiveDynamicAccess$$anonfun$createInstanceFor$2.apply(DynamicAccess.scala:78)
    at scala.util.Try$.apply(Try.scala:161)
    at akka.actor.ReflectiveDynamicAccess.createInstanceFor(DynamicAccess.scala:73)
    ... 64 more

将 TestActorRefs 与不扩展 Stash 的 actor 一起使用没有任何问题。所以我不知道这是配置错误还是我缺少的其他东西。

Answer 1

TestActorRef 不能与 Stash 一起使用。 TestActorRef 需要 CallingThreadMailbox，Stash 需要 DequeBasedMessageQueueSemantics。 The documentation should include this limitation and the error messages should be improved .