Polish concurrency in UserSessionResolver impl

spring-messaging/src/test/java/org/springframework/messaging/simp/handler/SimpleUserSessionResolverTests.java

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+/*
+ * 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.messaging.simp.handler;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.List;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+
+/**
+ * Test fixture for {@link SimpleUserSessionResolver}
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.0
+ */
+public class SimpleUserSessionResolverTests {
+
+	private static final String user = "joe";
+	private static final List<String> sessionIds = Arrays.asList("sess01", "sess02", "sess03");
+
+
+	@Test
+	public void addOneSessionId() {
+
+		SimpleUserSessionResolver resolver = new SimpleUserSessionResolver();
+		resolver.addUserSessionId(user, sessionIds.get(0));
+
+		assertEquals(Collections.singleton(sessionIds.get(0)), resolver.resolveUserSessionIds(user));
+		assertSame(Collections.emptySet(), resolver.resolveUserSessionIds("jane"));
+	}
+
+	@Test
+	public void addMultipleSessionIds() {
+
+		SimpleUserSessionResolver resolver = new SimpleUserSessionResolver();
+		for (String sessionId : sessionIds) {
+			resolver.addUserSessionId(user, sessionId);
+		}
+
+		assertEquals(new LinkedHashSet<>(sessionIds), resolver.resolveUserSessionIds(user));
+		assertEquals(Collections.emptySet(), resolver.resolveUserSessionIds("jane"));
+	}
+
+
+	@Test
+	public void removeSessionIds() {
+
+		SimpleUserSessionResolver resolver = new SimpleUserSessionResolver();
+		for (String sessionId : sessionIds) {
+			resolver.addUserSessionId(user, sessionId);
+		}
+
+		assertEquals(new LinkedHashSet<>(sessionIds), resolver.resolveUserSessionIds(user));
+
+		resolver.removeUserSessionId(user, sessionIds.get(1));
+		resolver.removeUserSessionId(user, sessionIds.get(2));
+		assertEquals(Collections.singleton(sessionIds.get(0)), resolver.resolveUserSessionIds(user));
+
+		resolver.removeUserSessionId(user, sessionIds.get(0));
+		assertSame(Collections.emptySet(), resolver.resolveUserSessionIds(user));
+	}
+
+}