Random merge queue in RefreshListenersTests

Author: albertzaharovits

server/src/test/java/org/elasticsearch/index/shard/RefreshListenersTests.java

@@ -42,6 +42,7 @@
 import org.elasticsearch.index.engine.EngineTestCase;
 import org.elasticsearch.index.engine.InternalEngine;
 import org.elasticsearch.index.engine.ThreadPoolMergeQueue;
+import org.elasticsearch.index.engine.ThreadPoolMergeScheduler;
 import org.elasticsearch.index.mapper.IdFieldMapper;
 import org.elasticsearch.index.mapper.LuceneDocument;
 import org.elasticsearch.index.mapper.MapperService;
@@ -99,8 +100,11 @@ public void setupListeners() throws Exception {
         maxListeners = randomIntBetween(2, 1000);
         // Now setup the InternalEngine which is much more complicated because we aren't mocking anything
         threadPool = new TestThreadPool(getTestName());
-        IndexSettings indexSettings = IndexSettingsModule.newIndexSettings("index", Settings.EMPTY);
-        threadPoolMergeQueue = ThreadPoolMergeQueue.maybeCreateThreadPoolMergeQueue(threadPool, indexSettings.getNodeSettings());
+        Settings settings = Settings.builder()
+            .put(ThreadPoolMergeScheduler.USE_THREAD_POOL_MERGE_SCHEDULER_SETTING.getKey(), randomBoolean())
+            .build();
+        IndexSettings indexSettings = IndexSettingsModule.newIndexSettings("index", settings);
+        threadPoolMergeQueue = ThreadPoolMergeQueue.maybeCreateThreadPoolMergeQueue(threadPool, settings);
         listeners = new RefreshListeners(
             () -> maxListeners,
             () -> engine.refresh("too-many-listeners"),