Akka/Scala example source code file (HotSwapSpec.scala)

This example Akka source code file (HotSwapSpec.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Akka and Scala source code examples by using tags.

All credit for the original source code belongs to akka.io; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Akka tags/keywords

actor, akka, akkaspec, an, becomer, crash, eventfilter, failure, hotswapspec, implicitsender, string, test, testing, testkit

The HotSwapSpec.scala Akka example source code

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 */

package akka.actor

import akka.testkit._

object HotSwapSpec {
  abstract class Becomer extends Actor {

  }
}

@org.junit.runner.RunWith(classOf[org.scalatest.junit.JUnitRunner])
class HotSwapSpec extends AkkaSpec with ImplicitSender {
  import HotSwapSpec.Becomer

  "An Actor" must {
    "be able to become in its constructor" in {
      val a = system.actorOf(Props(new Becomer {
        context.become { case always ⇒ sender() ! always }
        def receive = { case always ⇒ sender() ! "FAILURE" }
      }))
      a ! "pigdog"
      expectMsg("pigdog")
    }

    "be able to become multiple times in its constructor" in {
      val a = system.actorOf(Props(new Becomer {
        for (i ← 1 to 4) context.become({ case always ⇒ sender() ! i + ":" + always })
        def receive = { case always ⇒ sender() ! "FAILURE" }
      }))
      a ! "pigdog"
      expectMsg("4:pigdog")
    }

    "be able to become with stacking in its constructor" in {
      val a = system.actorOf(Props(new Becomer {
        context.become({ case always ⇒ sender() ! "pigdog:" + always; context.unbecome() }, false)
        def receive = { case always ⇒ sender() ! "badass:" + always }
      }))
      a ! "pigdog"
      expectMsg("pigdog:pigdog")
      a ! "badass"
      expectMsg("badass:badass")
    }

    "be able to become, with stacking, multiple times in its constructor" in {
      val a = system.actorOf(Props(new Becomer {
        for (i ← 1 to 4) context.become({ case always ⇒ sender() ! i + ":" + always; context.unbecome() }, false)
        def receive = { case always ⇒ sender() ! "FAILURE" }
      }))
      a ! "pigdog"
      a ! "pigdog"
      a ! "pigdog"
      a ! "pigdog"
      expectMsg("4:pigdog")
      expectMsg("3:pigdog")
      expectMsg("2:pigdog")
      expectMsg("1:pigdog")
    }

    "be able to hotswap its behavior with become(..)" in {
      val a = system.actorOf(Props(new Actor {
        def receive = {
          case "init" ⇒ sender() ! "init"
          case "swap" ⇒ context.become({ case x: String ⇒ context.sender() ! x })
        }
      }))

      a ! "init"
      expectMsg("init")
      a ! "swap"
      a ! "swapped"
      expectMsg("swapped")
    }

    "be able to revert hotswap its behavior with unbecome" in {
      val a = system.actorOf(Props(new Actor {
        def receive = {
          case "init" ⇒ sender() ! "init"
          case "swap" ⇒ context.become({
            case "swapped" ⇒ sender() ! "swapped"
            case "revert"  ⇒ context.unbecome()
          })
        }
      }))

      a ! "init"
      expectMsg("init")
      a ! "swap"

      a ! "swapped"
      expectMsg("swapped")

      a ! "revert"
      a ! "init"
      expectMsg("init")
    }

    "revert to initial state on restart" in {

      val a = system.actorOf(Props(new Actor {
        def receive = {
          case "state" ⇒ sender() ! "0"
          case "swap" ⇒
            context.become({
              case "state"   ⇒ sender() ! "1"
              case "swapped" ⇒ sender() ! "swapped"
              case "crash"   ⇒ throw new Exception("Crash (expected)!")
            })
            sender() ! "swapped"
        }
      }))
      a ! "state"
      expectMsg("0")
      a ! "swap"
      expectMsg("swapped")
      a ! "state"
      expectMsg("1")
      EventFilter[Exception](message = "Crash (expected)!", occurrences = 1) intercept { a ! "crash" }
      a ! "state"
      expectMsg("0")
    }
  }
}