Suggester suggester = createSuggester();

        // Multiple consecutive calls should be safe
        suggester.createIndexIfNothing();
        suggester.createIndexIfNothing();
        suggester.createIndexIfNothing();

        // Should still be able to use the index
        suggester.refresh();
        assertEquals("Index should work normally", 0, suggester.getAllWordsNum());

---

## Key Components

### Suggester (Main Entry Point)
Location: `src/main/java/org/codelibs/fess/suggest/Suggester.java`

Main operations: `suggest()`, `popularWords()`, `indexer()`, `createIndexIfNothing()`, `createNextIndex()`, `switchIndex()`, `removeDisableIndices()`

### SuggestIndexer (Indexing Engine)
Location: `src/main/java/org/codelibs/fess/suggest/index/SuggestIndexer.java`

 *   <li>{@link #refresh()}: Refreshes the suggestion indices.</li>
 *   <li>{@link #shutdown()}: Shuts down the thread pool.</li>
 *   <li>{@link #createIndexIfNothing()}: Creates a new index if no index exists.</li>
 *   <li>{@link #createNextIndex()}: Creates a new index and replaces the current update alias with the new index.</li>

        runner.admin().indices().prepareDelete("_all").execute().actionGet();
        runner.refresh();
        suggester = Suggester.builder().build(runner.client(), "PopularWordsRequestTest");
        suggester.createIndexIfNothing();
    }

    @Test
    public void test_basicRequest() throws Exception {
        indexQueryItems();

        PopularWordsResponse response = suggester.popularWords().setSize(10).execute().getResponse();

        runner.admin().indices().prepareDelete("_all").execute().actionGet();
        runner.refresh();
        suggester = Suggester.builder().build(runner.client(), "PopularWordsRequestBuilderTest");
        suggester.createIndexIfNothing();
    }

    @Test
    public void test_basicBuilder() throws Exception {
        indexItems();

        PopularWordsResponse response = suggester.popularWords().execute().getResponse();

        runner.admin().indices().prepareDelete("_all").execute().actionGet();
        runner.refresh();
        suggester = Suggester.builder().build(runner.client(), "SuggesterTest");
        suggester.createIndexIfNothing();
    }

    @Test
    public void test_Read() throws Exception {
        String indexName = "test-index";
        Client client = runner.client();
        SuggestSettings settings = suggester.settings();

        runner.admin().indices().prepareDelete("_all").execute().actionGet();
        runner.refresh();
        suggester = Suggester.builder().build(client, "ScrollTest");
        suggester.createIndexIfNothing();
    }

    @Test
    public void testScrollSearch_emptyResults() {
        // Create index without any documents
        createTestIndex();

                } catch (final SuggestSettingsException e) {
                    logger.warn("Failed to add suggest field: field={}", field, e);
                }
            }));
            suggester.createIndexIfNothing();
        } catch (final Exception e) {
            logger.warn("Failed to initialize Suggester.", e);
        }
    }

    /**
     * Gets the suggester instance.
     *

        runner.ensureYellow();
        suggester = Suggester.builder().build(runner.client(), "SuggesterTest");
        suggester.createIndexIfNothing();
    }

    @AfterClass
    public static void afterClass() throws Exception {
        runner.close();
        runner.clean();
    }

    @Before
    public void before() throws Exception {