OPEN - issue INT-567: Add round-robin dispatching strategy

http://jira.springframework.org/browse/INT-567

tidying in AbstractDispatcher, added LoadBalancingDispatcher
first Mockito testcase

org.springframework.integration/src/test/java/org/springframework/integration/dispatcher/LoadBalancingDispatcherTests.java

@@ -0,0 +1,61 @@
+/* Copyright 2002-2008 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.dispatcher;
+
+import static org.mockito.Mockito.*;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.runners.MockitoJUnit44Runner;
+import org.springframework.integration.core.Message;
+import org.springframework.integration.message.MessageHandler;
+
+/**
+ * 
+ * @author Iwein Fuld
+ * 
+ */
+@RunWith(MockitoJUnit44Runner.class)
+public class LoadBalancingDispatcherTests {
+
+	private LoadBalancingDispatcher dispatcher = new LoadBalancingDispatcher();
+
+	@Mock
+	private MessageHandler handler;
+
+	@Mock
+	private Message<?> message;
+
+	@Mock
+	private MessageHandler differentHandler;
+
+	@Test
+	public void dispatchMessageWithSingleHandler() throws Exception {
+		dispatcher.addHandler(handler);
+		dispatcher.dispatch(message);
+	}
+
+	@Test
+	public void differentHandlerInvokedOnSecondMessage() throws Exception {
+		dispatcher.addHandler(handler);
+		dispatcher.addHandler(differentHandler);
+		dispatcher.dispatch(message);
+		dispatcher.dispatch(message);
+		verify(handler).handleMessage(message);
+		verify(differentHandler).handleMessage(message);
+	}
+}