[Segment Replication] [Remote Store] Replace overriding mockInternalE…

…ngine() in test classes with NRTReplicationEngine. (opensearch-project#11716) (opensearch-project#11761)

* Replace overriding mockInternalEngine() in test classes with NRTReplicationEngine.



* remove unused comment.



* Add comment for explaining the conditional logic.



* Update comment with exact reason for conditional logic.



---------


(cherry picked from commit 3a3da4f)

Signed-off-by: Rishikesh1159 <rishireddy1159@gmail.com>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

server/src/internalClusterTest/java/org/opensearch/indices/replication/SegmentReplicationBaseIT.java

@@ -60,11 +60,6 @@ protected Collection<Class<? extends Plugin>> nodePlugins() {
         return asList(MockTransportService.TestPlugin.class);
     }
 
-    @Override
-    protected boolean addMockInternalEngine() {
-        return false;
-    }
-
     @Override
     public Settings indexSettings() {
         return Settings.builder()

server/src/internalClusterTest/java/org/opensearch/indices/replication/SegmentReplicationClusterSettingIT.java

@@ -52,11 +52,6 @@ public Settings indexSettings() {
             .build();
     }
 
-    @Override
-    protected boolean addMockInternalEngine() {
-        return false;
-    }
-
     public void testIndexReplicationSettingOverridesSegRepClusterSetting() throws Exception {
         Settings settings = Settings.builder().put(CLUSTER_SETTING_REPLICATION_TYPE, ReplicationType.SEGMENT).build();
         final String ANOTHER_INDEX = "test-index";

server/src/internalClusterTest/java/org/opensearch/remotestore/RemoteIndexPrimaryRelocationIT.java

@@ -35,11 +35,6 @@ protected Settings nodeSettings(int nodeOrdinal) {
             .build();
     }
 
-    @Override
-    protected boolean addMockInternalEngine() {
-        return false;
-    }
-
     public Settings indexSettings() {
         return Settings.builder()
             .put(super.indexSettings())

server/src/internalClusterTest/java/org/opensearch/remotestore/RemoteStoreBaseIntegTestCase.java

@@ -121,11 +121,6 @@ protected Map<String, Long> indexData(int numberOfIterations, boolean invokeFlus
         return indexingStats;
     }
 
-    @Override
-    protected boolean addMockInternalEngine() {
-        return false;
-    }
-
     @Override
     protected Settings nodeSettings(int nodeOrdinal) {
         if (segmentRepoPath == null || translogRepoPath == null) {

server/src/internalClusterTest/java/org/opensearch/remotestore/SegmentReplicationUsingRemoteStoreDisruptionIT.java

@@ -44,11 +44,6 @@ public Settings indexSettings() {
         return remoteStoreIndexSettings(1);
     }
 
-    @Override
-    protected boolean addMockInternalEngine() {
-        return false;
-    }
-
     public void testCancelReplicationWhileSyncingSegments() throws Exception {
         Path location = randomRepoPath().toAbsolutePath();
         setup(location, 0d, "metadata", Long.MAX_VALUE, 1);

server/src/internalClusterTest/java/org/opensearch/snapshots/SegmentReplicationSnapshotIT.java

@@ -74,11 +74,6 @@ public Settings restoreIndexDocRepSettings() {
         return Settings.builder().put(IndexMetadata.SETTING_REPLICATION_TYPE, ReplicationType.DOCUMENT).build();
     }
 
-    @Override
-    protected boolean addMockInternalEngine() {
-        return false;
-    }
-
     public void ingestData(int docCount, String indexName) throws Exception {
         for (int i = 0; i < docCount; i++) {
             client().prepareIndex(indexName).setId(Integer.toString(i)).setSource("field", "value" + i).execute().actionGet();

test/framework/src/main/java/org/opensearch/test/engine/MockEngineFactory.java

@@ -35,6 +35,7 @@
 import org.opensearch.index.engine.Engine;
 import org.opensearch.index.engine.EngineConfig;
 import org.opensearch.index.engine.EngineFactory;
+import org.opensearch.index.engine.NRTReplicationEngine;
 
 public final class MockEngineFactory implements EngineFactory {
 
@@ -46,6 +47,12 @@ public MockEngineFactory(Class<? extends FilterDirectoryReader> wrapper) {
 
     @Override
     public Engine newReadWriteEngine(EngineConfig config) {
-        return new MockInternalEngine(config, wrapper);
+
+        /**
+         * Segment replication enabled replicas (i.e. read only replicas) do not use an InternalEngine so a MockInternalEngine
+         * will not work and an NRTReplicationEngine must be used instead. The primary shards for these indexes will
+         * still use a MockInternalEngine.
+         */
+        return config.isReadOnlyReplica() ? new NRTReplicationEngine(config) : new MockInternalEngine(config, wrapper);
     }
 }