如何模拟子Actor以测试Akka系统？ [英] How to mock child Actors for testing an Akka system?

问题描述

当我在Akka中有一个父演员时，它会在初始化时直接创建一个子演员，当我想为父演员编写单元测试时，如何用TestProbe或模拟代替子演员？

When I have a parent actor in Akka, that directly creates a child actor on initialisation, when I want to write unit tests for the parent actor, how can I replace the child actor with a TestProbe or a mock?

例如，使用以下伪代码示例：

For example, with the following contrived code sample:

class TopActor extends Actor {
  val anotherActor = context.actorOf(AnotherActor.props, "anotherActor")

  override def receive: Receive = {
    case "call another actor" => anotherActor ! "hello"
  }
}

class AnotherActor extends Actor {

  override def recieve: Receive = {
    case "hello" => // do some stuff
  }

}

如果我要为TopActor编写测试，以检查发送给AnotherActor的消息是否为 hello，我如何替换执行AnotherActor？似乎TopActor是直接创建此子级的，因此访问起来并不容易。

If I want to write a test for TopActor, to check the message sent to AnotherActor is "hello", how do I replace the implementation of AnotherActor? It seems like TopActor creates this child directly so this is not easy to access.

推荐答案

以下方法似乎可行，但可以覆盖另一个演员的val直接看起来有点粗糙。我想知道是否还有其他更清洁/推荐的解决方案，这就是为什么即使我有这个有效答案，我仍然问这个问题的原因：

The following approach seems to work but overriding the val of anotherActor directly seems a little crude. I was wondering if there were any other cleaner/ recommended solutions, which is why I still asked the question even though I have this working answer:

class TopActorSpec extends MyActorTestSuiteTrait {
  it should "say hello to AnotherActor when receive 'call another actor'" {
    val testProbe = TestProbe()

    val testTopActor = TestActorRef(Props(new TopActor {
      override val anotherActor = testProbe.ref
    }))

    testTopActor ! "call another actor"
    testProbe.expectMsg(500 millis, "hello")
  }
}

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