Add UTs for getLuceneVersionForDocValuesUpdates()

Signed-off-by: Bhumika Saini <[email protected]>

server/src/main/java/org/opensearch/index/remote/RemoteStoreUtils.java

@@ -53,6 +53,12 @@ public static long invertLong(String str) {
         return Long.MAX_VALUE - num;
     }
 
+    /**
+     * Extracts the Lucene major version from the provided DocValuesUpdates file name
+     * @param filename DocValuesUpdates file name to parse
+     * @return Lucene major version that wrote the DocValuesUpdates file
+     * @throws CorruptIndexException If the Lucene major version cannot be inferred
+     */
     public static int getLuceneVersionForDocValuesUpdates(String filename) throws CorruptIndexException {
         // TODO: The following regex could work incorrectly if both major and minor versions are double-digits.
         // This is because the major and minor versions do not have a separator in the filename currently

server/src/test/java/org/opensearch/index/remote/RemoteStoreUtilsTests.java

@@ -8,6 +8,7 @@
 
 package org.opensearch.index.remote;
 
+import org.apache.lucene.index.CorruptIndexException;
 import org.opensearch.test.OpenSearchTestCase;
 
 public class RemoteStoreUtilsTests extends OpenSearchTestCase {
@@ -38,4 +39,12 @@ public void testinvert() {
             assertEquals(num, RemoteStoreUtils.invertLong(RemoteStoreUtils.invertLong(num)));
         }
     }
+
+    public void testGetLuceneVersionForDocValuesUpdates() throws CorruptIndexException {
+        assertEquals(9, RemoteStoreUtils.getLuceneVersionForDocValuesUpdates("_0_1_Lucene90_0.dvm"));
+    }
+
+    public void testGetLuceneVersionForDocValuesUpdatesException() {
+        assertThrows(CorruptIndexException.class, () -> RemoteStoreUtils.getLuceneVersionForDocValuesUpdates("_0_1_Asserting_0.dvm"));
+    }
 }