Add test that ES filterreader getCoreCacheKey() behaves correctly.

Closes #8831.

src/test/java/org/elasticsearch/common/lucene/index/ElasticsearchDirectoryReaderTests.java

@@ -0,0 +1,76 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch 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.elasticsearch.common.lucene.index;
+
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.StringField;
+import org.apache.lucene.index.DirectoryReader;
+import org.apache.lucene.index.IndexWriter;
+import org.apache.lucene.index.IndexWriterConfig;
+import org.apache.lucene.index.NoMergePolicy;
+import org.apache.lucene.index.Term;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.util.IOUtils;
+import org.elasticsearch.index.Index;
+import org.elasticsearch.index.shard.ShardId;
+import org.elasticsearch.test.ElasticsearchLuceneTestCase;
+
+/** Simple tests for this filterreader */
+public class ElasticsearchDirectoryReaderTests extends ElasticsearchLuceneTestCase {
+    
+    /** Test that core cache key (needed for NRT) is working */
+    public void testCoreCacheKey() throws Exception {
+        Directory dir = newDirectory();
+        IndexWriterConfig iwc = new IndexWriterConfig(null);
+        iwc.setMaxBufferedDocs(100);
+        iwc.setMergePolicy(NoMergePolicy.INSTANCE);
+        IndexWriter iw = new IndexWriter(dir, iwc);
+        
+        // add two docs, id:0 and id:1
+        Document doc = new Document();
+        Field idField = new StringField("id", "", Field.Store.NO);
+        doc.add(idField);
+        idField.setStringValue("0");
+        iw.addDocument(doc);
+        idField.setStringValue("1");
+        iw.addDocument(doc);
+        
+        // open reader
+        ShardId shardId = new ShardId(new Index("fake"), 1);
+        DirectoryReader ir = ElasticsearchDirectoryReader.wrap(DirectoryReader.open(iw, true), shardId);
+        assertEquals(2, ir.numDocs());
+        assertEquals(1, ir.leaves().size());
+
+        // delete id:0 and reopen
+        iw.deleteDocuments(new Term("id", "0"));
+        DirectoryReader ir2 = DirectoryReader.openIfChanged(ir);
+        
+        // we should have the same cache key as before
+        assertEquals(1, ir2.numDocs());
+        assertEquals(1, ir2.leaves().size());
+        assertSame(ir.leaves().get(0).reader().getCoreCacheKey(), ir2.leaves().get(0).reader().getCoreCacheKey());
+        
+        // this is kind of stupid, but for now its here
+        assertNotSame(ir.leaves().get(0).reader().getCombinedCoreAndDeletesKey(), ir2.leaves().get(0).reader().getCombinedCoreAndDeletesKey());
+        
+        IOUtils.close(ir, ir2, iw, dir);
+    }
+}