Added FailureParent example

Author: jamie-allen

chapter04/src/test/scala/com/reactivedesignpatterns/chapter4/FailureParentSpec.scala

@@ -0,0 +1,37 @@
+package com.reactivedesignpatterns.chapter4
+
+import org.scalatest._
+import akka.actor._
+import akka.actor.SupervisorStrategy.Stop
+import akka.testkit.TestProbe
+
+class FailureParentSpec extends WordSpec with Matchers with BeforeAndAfterAll {
+	"Using a FailureParent" must {
+	  "Result in failures being collected and returned" in {
+		  implicit val system = ActorSystem()
+		  val failures = TestProbe()
+			val failureParent = system.actorOf(Props(new FailureParent(failures.ref)))
+			failureParent ! TestFailureParentMessage
+			failures.expectMsgType[NullPointerException]
+	  }
+	}
+}
+
+case object TestFailureParentMessage 
+
+class FailureParent(failures: ActorRef) extends Actor {
+	val props = Props[MyFailureParentActor]
+  val child = context.actorOf(props, "child")
+  override val supervisorStrategy = OneForOneStrategy() {
+    case f => failures ! f; Stop
+  }
+  def receive = {
+    case msg => child forward msg
+  }
+}
+
+class MyFailureParentActor extends Actor {
+  def receive = {
+    case _ => throw new NullPointerException
+  }
+}