Scala 为什么我的Akka FSM活动超时？

作为Akka FSM的学习练习，我在一家咖啡店模拟了一个简化的订单处理流程。附件是状态转换图。然而，我写的一个测试用例超时了，我不明白为什么

FSM（为简洁起见，未显示案例类别）：

测试失败：

it should "stay in OrderPlaced state as long as customer has not paid" in {
    val orderSystem = system.actorOf(Props[OrderSystem])
    orderSystem ! BaristaIsAvailable(OrderPending, PaymentPending)

    orderSystem ! SubscribeTransitionCallBack(testActor)

    expectMsg(CurrentState(orderSystem, OrderPlaced))

    orderSystem ! BaristaIsAvailable(OrderPlaced, PaymentPending)

    expectMsg(CurrentState(orderSystem, OrderPlaced))
}

日志：

---

SubscribeTransitionCallBack

将只传递一次

当前状态

，然后只传递

转换

回调

您可以尝试这样做：

it should "stay in OrderPlaced state as long as customer has not paid" in {

  val orderSystem = TestFSMRef(new OrderSystem)

  orderSystem ! SubscribeTransitionCallBack(testActor)
  // fsm first answers with current state
  expectMsgPF(1.second. s"OrderPending as current state for $orderSystem") { 
    case CurrentState('orderSystem', OrderPending) => ok 
  }

  // from now on the subscription will yield 'Transition' messages
  orderSystem ! BaristaIsAvailable(OrderPending, PaymentPending)
  expectMsgPF(1.second, s"Transition from OrderPending to OrderPlaced for $orderSystem") { 
    case Transition(`orderSystem`, OrderPending, OrderPlaced) => ok 
  }

  orderSystem ! BaristaIsAvailable(OrderPlaced, PaymentPending)
  // there is no transition, so there should not be a callback.
  expectNoMsg(1.second)

/*
  // alternatively, if your state data changes, using TestFSMRef, you could check state data blocking for some time
  awaitCond(
    p = orderSystem.stateData == ???, 
    max = 2.seconds, 
    interval = 200.millis,
    message = "waiting for expected state data..."
  )
  // awaitCond will throw an exception if the condition is not met within max timeout
*/
  success
}

---

您并没有从FSM发回任何回复，您的expectMsg失败是正常的，因为在测试中会看到一个探针。这对我的案子有用吗<代码>val probe=TestProbe（）；expectMsg@AbhijitSarkar在测试用例中使用

TestProbe

肯定是一种可行的方法。但是它使事情变得更加复杂，而不是改善任何事情。最后一个问题。在上面的日志中，我看到当我发送第二个事件时，它不仅改变了状态，而且匹配了案例4（在日志中打印为4）。这是预期的行为，如果我对不匹配的事件使用

goto

，它将进入该状态，但不匹配任何

case

语句。如果将

goto

用于与匹配的事件，则它将进入新状态，并与

案例

匹配？@AbhijitSarkar我不理解这个问题。但是我要说的是，对于第二条消息，我们完全希望事件与

when（OrderPlaced）

state函数中的案例4匹配。由于第一个案例与错误的

数据不匹配，案例2和3与消息本身不匹配，案例4与任何消息匹配，而
stateData与数据（uu，PaymentPending）
，这是您在
when（OrderPending）
状态函数的第一条消息后设置的。顺便说一句，案例4以不改变状态的
stay（）
结束。
2015-09-22 23:29:15.236 [order-system-akka.actor.default-dispatcher-2] [DEBUG] n.a.s.o.OrderSystem - processing Event(BaristaIsAvailable(OrderPending,PaymentPending),Data(OrderPending,PaymentPending)) from Actor[akka://order-system/system/testActor1#-2143558060]
2015-09-22 23:29:15.238 [order-system-akka.actor.default-dispatcher-2] [INFO ] n.a.s.o.OrderSystem - Entering state: OrderPlaced with payment activity: PaymentPending from state: OrderPending with payment activity: PaymentPending.
2015-09-22 23:29:15.239 [order-system-akka.actor.default-dispatcher-2] [DEBUG] n.a.s.o.OrderSystem - transition OrderPending -> OrderPlaced
4
2015-09-22 23:29:15.242 [order-system-akka.actor.default-dispatcher-2] [DEBUG] n.a.s.o.OrderSystem - processing Event(BaristaIsAvailable(OrderPlaced,PaymentPending),Data(OrderPending,PaymentPending)) from Actor[akka://order-system/system/testActor1#-2143558060]
[31m- should stay in OrderPlaced state as long as customer has not paid *** FAILED ***[0m
[31m  java.lang.AssertionError: assertion failed: timeout (3 seconds)

it should "stay in OrderPlaced state as long as customer has not paid" in {

  val orderSystem = TestFSMRef(new OrderSystem)

  orderSystem ! SubscribeTransitionCallBack(testActor)
  // fsm first answers with current state
  expectMsgPF(1.second. s"OrderPending as current state for $orderSystem") { 
    case CurrentState('orderSystem', OrderPending) => ok 
  }

  // from now on the subscription will yield 'Transition' messages
  orderSystem ! BaristaIsAvailable(OrderPending, PaymentPending)
  expectMsgPF(1.second, s"Transition from OrderPending to OrderPlaced for $orderSystem") { 
    case Transition(`orderSystem`, OrderPending, OrderPlaced) => ok 
  }

  orderSystem ! BaristaIsAvailable(OrderPlaced, PaymentPending)
  // there is no transition, so there should not be a callback.
  expectNoMsg(1.second)

/*
  // alternatively, if your state data changes, using TestFSMRef, you could check state data blocking for some time
  awaitCond(
    p = orderSystem.stateData == ???, 
    max = 2.seconds, 
    interval = 200.millis,
    message = "waiting for expected state data..."
  )
  // awaitCond will throw an exception if the condition is not met within max timeout
*/
  success
}