Add MongoSession.isExpired interval < 0 Test

Issue gh-629

spring-session/src/test/java/org/springframework/session/data/mongo/MongoExpiringSessionTests.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2014-2016 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.mongo;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Rob Winch
+ */
+public class MongoExpiringSessionTests {
+
+	@Test
+	public void isExpiredWhenIntervalNegativeThenFalse() {
+		MongoExpiringSession session = new MongoExpiringSession();
+		session.setMaxInactiveIntervalInSeconds(-1);
+		session.setLastAccessedTime(0L);
+
+		assertThat(session.isExpired()).isFalse();
+	}
+}