Add SessionDestroyedEvent

Add support for SessionDestroyedEvent so that applications can detect
when a Spring Session has expired or explicitly deleted. This will
ensure that we can cleanup resources (i.e. WebSockets) can be cleaned up
when a Session ends.

Fixes gh-60

spring-session/src/test/java/org/springframework/session/data/redis/SessionMessageListenerTests.java

@@ -0,0 +1,139 @@
+/*
+ * Copyright 2002-2013 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.session.data.redis;
+
+import static org.fest.assertions.Assertions.assertThat;
+import static org.mockito.Mockito.*;
+
+import java.io.UnsupportedEncodingException;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Captor;
+import org.mockito.Mock;
+import org.mockito.runners.MockitoJUnitRunner;
+import org.springframework.context.ApplicationEvent;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.data.redis.connection.Message;
+import org.springframework.session.events.SessionDestroyedEvent;
+
+
+/**
+ *
+ * @author Rob Winch
+ *
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class SessionMessageListenerTests {
+    @Mock
+    ApplicationEventPublisher eventPublisher;
+
+    @Mock
+    Message message;
+
+    @Captor
+    ArgumentCaptor<SessionDestroyedEvent> event;
+
+    byte[] pattern;
+
+    SessionMessageListener listener;
+
+    @Before
+    public void setup() {
+        listener = new SessionMessageListener(eventPublisher);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void constructorNullEventPublisher() {
+        new SessionMessageListener(null);
+    }
+
+    @Test
+    public void onMessageNullBody() throws Exception {
+        listener.onMessage(message, pattern);
+
+        verifyZeroInteractions(eventPublisher);
+    }
+
+    @Test
+    public void onMessageDel() throws Exception {
+        mockMessage("del","spring:sessions:session:123");
+
+        listener.onMessage(message, pattern);
+
+        verify(eventPublisher).publishEvent(event.capture());
+        assertThat(event.getValue().getSessionId()).isEqualTo("123");
+    }
+
+    @Test
+    public void onMessageSource() throws Exception {
+        mockMessage("del","spring:sessions:session:123");
+
+        listener.onMessage(message, pattern);
+
+        verify(eventPublisher).publishEvent(event.capture());
+        assertThat(event.getValue().getSource()).isEqualTo(listener);
+    }
+
+    @Test
+    public void onMessageExpired() throws Exception {
+        mockMessage("expired","spring:sessions:session:543");
+
+        listener.onMessage(message, pattern);
+
+        verify(eventPublisher).publishEvent(event.capture());
+        assertThat(event.getValue().getSessionId()).isEqualTo("543");
+    }
+
+    @Test
+    public void onMessageHset() throws Exception {
+        mockMessage("hset","spring:sessions:session:123");
+
+        listener.onMessage(message, pattern);
+
+        verifyZeroInteractions(eventPublisher);
+    }
+
+    @Test
+    public void onMessageRename() throws Exception {
+        mockMessage("rename","spring:sessions:session:123");
+
+        listener.onMessage(message, pattern);
+
+        verifyZeroInteractions(eventPublisher);
+    }
+
+    @Test
+    public void onMessageEventPublisherErrorCaught() throws Exception {
+        mockMessage("del","spring:sessions:session:123");
+        doThrow(new IllegalStateException("Test Exceptions are caught")).when(eventPublisher).publishEvent(any(ApplicationEvent.class));
+
+        listener.onMessage(message, pattern);
+
+        verify(eventPublisher).publishEvent(any(ApplicationEvent.class));
+    }
+
+    private void mockMessage(String body, String channel) throws UnsupportedEncodingException {
+        when(message.getBody()).thenReturn(bytes(body));
+        when(message.getChannel()).thenReturn(bytes(channel));
+    }
+
+    private static byte[] bytes(String s) throws UnsupportedEncodingException {
+        return s.getBytes("UTF-8");
+    }
+}