}

    // Test run method with null DataService
    public void test_run_nullDataService() {
        indexUpdater.dataService = null;
        try {
            indexUpdater.run();
            fail("Should throw FessSystemException");
        } catch (FessSystemException e) {
            assertEquals("DataService is null.", e.getMessage());
        }
    }

    /** OpenSearch client for index operations */
    @Resource
    protected SearchEngineClient searchEngineClient;

    /** Service for managing crawled document data */
    @Resource
    protected DataService<OpenSearchAccessResult> dataService;

    /** Service for managing URL crawling queue */
    @Resource
    protected UrlQueueService<OpenSearchUrlQueue> urlQueueService;

    /** Service for URL filtering operations */

   * Example usage:
   *
   * {@snippet :
   * FluentFuture<RowKey> rowKeyFuture = FluentFuture.from(indexService.lookUp(query));
   * ListenableFuture<QueryResult> queryFuture =
   *     rowKeyFuture.transformAsync(dataService::readFuture, executor);
   * }
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See

   * Example usage:
   *
   * {@snippet :
   * ListenableFuture<RowKey> rowKeyFuture = indexService.lookUp(query);
   * ListenableFuture<QueryResult> queryFuture =
   *     transformAsync(rowKeyFuture, dataService::readFuture, executor);
   * }
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See
   * the warnings the {@link MoreExecutors#directExecutor} documentation.
   *