Logging fix in NettyMessagingService + Added a simple unit test.

@@ -241,8 +241,9 @@ public class NettyMessagingService implements MessagingService {
                         NettyMessagingService.this.responseFutures.getIfPresent(message.id());
                     if (futureResponse != null) {
                         futureResponse.setResponse(message.payload());
+                    } else {
+                        log.warn("Received a reply. But was unable to locate the request handle");
                     }
-                    log.warn("Received a reply. But was unable to locate the request handle");
                 } finally {
                     NettyMessagingService.this.responseFutures.invalidate(message.id());
                 }

+package org.onlab.netty;
+
+import java.util.concurrent.TimeUnit;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Simple ping-pong test that exercises NettyMessagingService.
+ */
+public class PingPongTest {
+
+    @Test
+    public void testPingPong() throws Exception {
+        NettyMessagingService pinger = new NettyMessagingService(8085);
+        NettyMessagingService ponger = new NettyMessagingService(9086);
+        try {
+            pinger.activate();
+            ponger.activate();
+            pinger.setPayloadSerializer(new KryoSerializer());
+            ponger.setPayloadSerializer(new KryoSerializer());
+            ponger.registerHandler("echo", new EchoHandler());
+            Response<String> response = pinger.sendAndReceive(new Endpoint("localhost", 9086), "echo", "hello");
+            Assert.assertEquals("hello", response.get(10000, TimeUnit.MILLISECONDS));
+        } finally {
+            pinger.deactivate();
+            ponger.deactivate();
+        }
+    }
+}