测试创建子参与者的参与者

Question

例如，我有两个演员——一个家长演员和一个孩子演员。当父级收到消息时，它会产生消息中指定的尽可能多的子角色。如何测试此功能？有没有一种方法可以模拟上下文，或者其他一些方法来检查参与者的创建是否正确和数量是否正确？

class ParentActor extends Actor {
  case class CreateChildren(count: Int)

  override def receive: Receive = {
    case CreateChildren(count) => for (_ <- 0 until count) context.actorOf(Props[ChildActor])
  }
}

class ChildActor extends Actor {
  override def receive: Receive = {
    case _ =>
  }
}

更新：基于@Tim answer的解决方案

更改类别：

class ParentActor(childActorFactory: ChildActorFactory) extends Actor {
  override def receive: Receive = {
    case CreateChildren(count) => for (_ <- 0 until count) childActorFactory.create(context)
  }
}

object ParentActor {
  def props(childActorFactory: ChildActorFactory): Props = Props(new ParentActor(childActorFactory))
}

class ChildActorFactory {
  def create(context: ActorContext): ActorRef = context.actorOf(Props[ChildActor])
}

测试：

"ParentActor" should {
    "instantiate ten child actors" in {
      val childrenCount = 10
      val childActorFactory = mock[ChildActorFactory]
      val parentActor = TestActorRef[ParentActor](ParentActor.props(childActorFactory))

      parentActor ! CreateChildren(childrenCount)

      Mockito.verify(childActorFactory, Mockito.times(childrenCount))
        .create(parentActor.underlyingActor.context)
    }
  }

Answer 1

确保创建子角色的最简单方法是重写ChildActor中的preStart（）方法

class ChildActor extendsActor with ActorLogging {
  override def preStart(): Unit = log.info("Child created")
def receive(): Receive = // whatever
}

因此，每次向系统添加子角色时，您都会看到该消息。

Answer 2

如果要完全测试父参与者，则需要模拟子参与者，因此不能直接在父参与者中创建子参与者。相反，将工厂方法传递给父参与者（依赖项注入）：

class ParentActor(makeChild: () => ChildActor) extends Actor {
  case class CreateChildren(count: Int)

  override def receive: Receive = {
    case CreateChildren(count) => for (_ <- 0 until count) makeChild() 
  }
}

makeChild函数可以计算创建的参与者数量。它还可以返回一个模拟版本的ChildActor，该版本实现了测试行为，以强调ParentActor。