ZeroMQ module's ConcurrentSocketActorSpec fails.

* Fixed usage of extension. See #1746
* Clarified usage of load extensions in docs. See #1745

akka-docs/java/extending-akka.rst

@@ -54,6 +54,12 @@ Loading from Configuration
 To be able to load extensions from your Akka configuration you must add FQCNs of implementations of either ``ExtensionId`` or ``ExtensionIdProvider``
 in the "akka.extensions" section of the config you provide to your ``ActorSystem``.
 
+::
+
+    akka {
+      extensions = ["akka.docs.extension.ExtensionDocTestBase.CountExtension"]
+    }
+
 Applicability
 =============
 

akka-docs/scala/code/akka/docs/extension/ExtensionDocSpec.scala

@@ -41,6 +41,15 @@ object CountExtension
 //#extensionid
 
 object ExtensionDocSpec {
+
+  val config = """
+    //#config
+    akka {
+      extensions = ["akka.docs.extension.CountExtension$"]
+    }
+    //#config
+    """
+
   //#extension-usage-actor
 
   class MyActor extends Actor {
@@ -64,7 +73,7 @@ object ExtensionDocSpec {
   //#extension-usage-actor-trait
 }
 
-class ExtensionDocSpec extends AkkaSpec {
+class ExtensionDocSpec extends AkkaSpec(ExtensionDocSpec.config) {
   import ExtensionDocSpec._
 
   "demonstrate how to create an extension in Scala" in {
@@ -73,4 +82,10 @@ class ExtensionDocSpec extends AkkaSpec {
     //#extension-usage
   }
 
+  "demonstrate how to lookup a configured extension in Scala" in {
+    //#extension-lookup
+    system.extension(CountExtension)
+    //#extension-lookup
+  }
+
 }

akka-docs/scala/extending-akka.rst

@@ -48,6 +48,11 @@ Loading from Configuration
 To be able to load extensions from your Akka configuration you must add FQCNs of implementations of either ``ExtensionId`` or ``ExtensionIdProvider``
 in the ``akka.extensions`` section of the config you provide to your ``ActorSystem``.
 
+.. includecode:: code/akka/docs/extension/ExtensionDocSpec.scala
+   :include: config
+
+Note that in this case ``CountExtension`` is an object and therefore the class name ends with ``$``.
+
 Applicability
 =============
 

akka-zeromq/src/test/scala/akka/zeromq/ConcurrentSocketActorSpec.scala

@@ -9,11 +9,7 @@ import akka.util.duration._
 import akka.actor.{ Cancellable, Actor, Props, ActorRef }
 
 object ConcurrentSocketActorSpec {
-  val config = """
+  val config = ""
-akka {
-  extensions = ["akka.zeromq.ZeroMQExtension"]
-}
-"""
 }
 
 class ConcurrentSocketActorSpec
@@ -23,7 +19,7 @@ class ConcurrentSocketActorSpec
 
   val endpoint = "tcp://127.0.0.1:%s" format { val s = new java.net.ServerSocket(0); try s.getLocalPort finally s.close() }
 
-  def zmq = system.extension(ZeroMQExtension)
+  def zmq = ZeroMQExtension(system)
 
   "ConcurrentSocketActor" should {
     "support pub-sub connections" in {