Introduce LogoutSuccessEvent

LogoutSuccessEvent is a simple AbstractAuthenticationEvent implementation which indicates successful logout.

By default, LogoutConfigurer will add a new LogoutHandler called LogoutSuccessEventPublishingLogoutHandler to publish this event.

This PR will also fix ConcurrentSessionFilter's composite logoutHandler, now will get LogoutHandler instances from LogoutConfigurer for consistency.

Fixes gh-2900

web/src/test/java/org/springframework/security/web/authentication/logout/LogoutSuccessEventPublishingLogoutHandlerTests.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2002-2019 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
+ *
+ *      https://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.security.web.authentication.logout;
+
+import org.junit.Test;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.security.authentication.event.LogoutSuccessEvent;
+import org.springframework.security.core.Authentication;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+/**
+ * @author Onur Kagan Ozcan
+ */
+public class LogoutSuccessEventPublishingLogoutHandlerTests {
+
+	@Test
+	public void shouldPublishEvent() {
+		LogoutSuccessEventPublishingLogoutHandler handler = new LogoutSuccessEventPublishingLogoutHandler();
+		LogoutAwareEventPublisher eventPublisher = new LogoutAwareEventPublisher();
+		handler.setApplicationEventPublisher(eventPublisher);
+
+		handler.logout(new MockHttpServletRequest(), new MockHttpServletResponse(), mock(Authentication.class));
+
+		assertThat(eventPublisher.flag).isTrue();
+	}
+
+	@Test
+	public void shouldNotPublishEventWhenAuthenticationIsNull() {
+		LogoutSuccessEventPublishingLogoutHandler handler = new LogoutSuccessEventPublishingLogoutHandler();
+		LogoutAwareEventPublisher eventPublisher = new LogoutAwareEventPublisher();
+		handler.setApplicationEventPublisher(eventPublisher);
+
+		handler.logout(new MockHttpServletRequest(), new MockHttpServletResponse(), null);
+
+		assertThat(eventPublisher.flag).isFalse();
+	}
+
+	private static class LogoutAwareEventPublisher implements ApplicationEventPublisher {
+
+		Boolean flag = false;
+
+		@Override
+		public void publishEvent(Object event) {
+			if (LogoutSuccessEvent.class.isAssignableFrom(event.getClass())) {
+				flag = true;
+			}
+		}
+	}
+}

web/src/test/java/org/springframework/security/web/concurrent/ConcurrentSessionFilterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
+ * Copyright 2002-2019 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.
@@ -17,6 +17,7 @@
 package org.springframework.security.web.concurrent;
 
 import java.util.Date;
+import java.util.List;
 
 import javax.servlet.FilterChain;
 import javax.servlet.http.HttpServletRequest;
@@ -53,6 +54,7 @@ import static org.mockito.Mockito.when;
  *
  * @author Ben Alex
  * @author Luke Taylor
+ * @author Onur Kagan Ozcan
  */
 public class ConcurrentSessionFilterTests {
 
@@ -315,7 +317,7 @@ public class ConcurrentSessionFilterTests {
 	public void setLogoutHandlersWhenNullThenThrowsException() {
 		ConcurrentSessionFilter filter = new ConcurrentSessionFilter(new SessionRegistryImpl());
 
-		filter.setLogoutHandlers(null);
+		filter.setLogoutHandlers((List<LogoutHandler>) null);
 	}
 
 	@Test(expected = IllegalArgumentException.class)