Revert "Removed ResizerSpec test violating routing rules"

This reverts commit 162d59db35.

akka-actor-tests/src/test/scala/akka/routing/ResizerSpec.scala

@@ -128,6 +128,36 @@ class ResizerSpec extends AkkaSpec(ResizerSpec.config) with DefaultTimeout with
       current.routees.size must be(2)
     }
 
+    // FIXME this test violates the rule that you can not use a BalancingDispatcher with any kind of Router - now throws a ConfigurationException in verification process
+    "resize when busy" ignore {
+
+      val busy = new TestLatch(1)
+
+      val resizer = DefaultResizer(
+        lowerBound = 1,
+        upperBound = 3,
+        pressureThreshold = 0,
+        messagesPerResize = 1)
+
+      val router = system.actorOf(Props[BusyActor].withRouter(RoundRobinRouter(resizer = Some(resizer))).withDispatcher("bal-disp"))
+
+      val latch1 = new TestLatch(1)
+      router ! (latch1, busy)
+      Await.ready(latch1, 2 seconds)
+
+      val latch2 = new TestLatch(1)
+      router ! (latch2, busy)
+      Await.ready(latch2, 2 seconds)
+
+      val latch3 = new TestLatch(1)
+      router ! (latch3, busy)
+      Await.ready(latch3, 2 seconds)
+
+      Await.result(router ? CurrentRoutees, 5 seconds).asInstanceOf[RouterRoutees].routees.size must be(3)
+
+      busy.countDown()
+    }
+
     "grow as needed under pressure" in {
       // make sure the pool starts at the expected lower limit and grows to the upper as needed
       // as influenced by the backlog of blocking pooled actors