ATLAS-361 Add validation when index backends are switched in ATLAS configuration…

repository/src/test/java/org/apache/atlas/repository/graph/TitanGraphProviderTest.java

+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.atlas.repository.graph;
+
+import com.thinkaurelius.titan.core.TitanGraph;
+import com.thinkaurelius.titan.core.util.TitanCleanup;
+import com.thinkaurelius.titan.diskstorage.Backend;
+import com.thinkaurelius.titan.graphdb.database.StandardTitanGraph;
+import org.apache.atlas.ApplicationProperties;
+import org.apache.atlas.AtlasException;
+import org.apache.commons.configuration.Configuration;
+import org.mockito.Mockito;
+import org.testng.Assert;
+import org.testng.annotations.AfterClass;
+import org.testng.annotations.BeforeTest;
+import org.testng.annotations.Test;
+
+@Test
+public class TitanGraphProviderTest {
+
+   private Configuration configuration;
+   private TitanGraph graph;
+
+   @BeforeTest
+   public void setUp() throws AtlasException {
+       //First get Instance
+       graph = TitanGraphProvider.getGraphInstance();
+       configuration = ApplicationProperties.getSubsetConfiguration(ApplicationProperties.get(), TitanGraphProvider.GRAPH_PREFIX);
+   }
+
+    @AfterClass
+    public void tearDown() throws Exception {
+        try {
+            graph.shutdown();
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+
+        try {
+            TitanCleanup.clear(graph);
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+   @Test
+   public void testValidate() throws AtlasException {
+       try {
+           TitanGraphProvider.validateIndexBackend(configuration);
+       } catch(Exception e){
+           Assert.fail("Unexpected exception ", e);
+       }
+
+       //Change backend
+       configuration.setProperty(TitanGraphProvider.INDEX_BACKEND_CONF, TitanGraphProvider.INDEX_BACKEND_LUCENE);
+       try {
+           TitanGraphProvider.validateIndexBackend(configuration);
+           Assert.fail("Expected exception");
+       } catch(Exception e){
+           Assert.assertEquals(e.getMessage(), "Configured Index Backend lucene differs from earlier configured Index Backend elasticsearch. Aborting!");
+       }
+   }
+}