Verify config override of router nr-of-instances. See #1607

* It wasn't a bug. I think the confusion came from config without 'router' defined.
* Added test
* Added some clarification to docs

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

@@ -15,6 +15,15 @@ import com.typesafe.config.ConfigFactory
 
 object RoutingSpec {
 
+  val config = """
+    akka.actor.deployment {
+      /router1 {
+        router = round-robin
+        nr-of-instances = 3
+      }
+    }
+    """
+
   class TestActor extends Actor {
     def receive = {
       case _ ⇒
@@ -31,7 +40,7 @@ object RoutingSpec {
 }
 
 @org.junit.runner.RunWith(classOf[org.scalatest.junit.JUnitRunner])
-class RoutingSpec extends AkkaSpec with DefaultTimeout with ImplicitSender {
+class RoutingSpec extends AkkaSpec(RoutingSpec.config) with DefaultTimeout with ImplicitSender {
 
   import akka.routing.RoutingSpec._
 
@@ -87,6 +96,18 @@ class RoutingSpec extends AkkaSpec with DefaultTimeout with ImplicitSender {
       Await.ready(doneLatch, 1 seconds)
     }
 
+    "use configured nr-of-instances when FromConfig" in {
+      val router = system.actorOf(Props[TestActor].withRouter(FromConfig), "router1")
+      Await.result(router ? CurrentRoutees, 5 seconds).asInstanceOf[RouterRoutees].routees.size must be(3)
+      system.stop(router)
+    }
+
+    "use configured nr-of-instances when router is specified" in {
+      val router = system.actorOf(Props[TestActor].withRouter(RoundRobinRouter(nrOfInstances = 2)), "router1")
+      Await.result(router ? CurrentRoutees, 5 seconds).asInstanceOf[RouterRoutees].routees.size must be(3)
+      system.stop(router)
+    }
+
   }
 
   "no router" must {

akka-actor/src/main/resources/reference.conf

@@ -76,6 +76,7 @@ akka {
         #   supplied in the source code (overridable using create-as below)
         # - routees.paths: will look the paths up using actorFor and route to
         #   them, i.e. will not create children
+        # - resizer: dynamically resizable number of routees as specified in resizer below
         router = "from-code"
 
         # number of children to create in case of a non-direct router; this setting

akka-docs/java/routing.rst

@@ -44,8 +44,9 @@ You can also give the router already created routees as in:
 When you create a router programatically you define the number of routees *or* you pass already created routees to it.
 If you send both parameters to the router *only* the latter will be used, i.e. ``nrOfInstances`` is disregarded.
 
-*It is also worth pointing out that if you define the number of routees in the configuration file then this
-value will be used instead of any programmatically sent parameters.*
+*It is also worth pointing out that if you define the number of routees (``nr-of-instances`` or  ``routees``) in
+the configuration file then this value will be used instead of any programmatically sent parameters, but you must
+also define the ``router`` property in the configuration.*
 
 Once you have the router actor it is just to send messages to it as you would to any actor:
 
@@ -189,6 +190,9 @@ This is an example of how to programatically create a resizable router:
 
 .. includecode:: code/akka/docs/jrouting/RouterViaProgramExample.java#programmaticRoutingWithResizer
 
+*It is also worth pointing out that if you define the ``router`` in the configuration file then this value
+will be used instead of any programmatically sent parameters.*
+
 Custom Router
 ^^^^^^^^^^^^^
 

akka-docs/scala/routing.rst

@@ -44,8 +44,9 @@ You can also give the router already created routees as in:
 When you create a router programatically you define the number of routees *or* you pass already created routees to it.
 If you send both parameters to the router *only* the latter will be used, i.e. ``nrOfInstances`` is disregarded.
 
-*It is also worth pointing out that if you define the number of routees in the configuration file then this
-value will be used instead of any programmatically sent parameters.*
+*It is also worth pointing out that if you define the number of routees (``nr-of-instances`` or  ``routees``) in
+the configuration file then this value will be used instead of any programmatically sent parameters, but you must
+also define the ``router`` property in the configuration.*
 
 Once you have the router actor it is just to send messages to it as you would to any actor:
 
@@ -190,6 +191,8 @@ This is an example of how to programatically create a resizable router:
 
 .. includecode:: code/akka/docs/routing/RouterViaProgramExample.scala#programmaticRoutingWithResizer
 
+*It is also worth pointing out that if you define the ``router`` in the configuration file then this value
+will be used instead of any programmatically sent parameters.*
 
 Custom Router
 ^^^^^^^^^^^^^