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>

        final Suggester suggester = Suggester.builder().build(client, "resource-test");

        // createIndexIfNothing internally calls getDefaultMappings and getDefaultIndexSettings
        boolean created = suggester.createIndexIfNothing();

        assertTrue("Index should be created successfully", created);

        // Verify index exists

        public MockSuggestSettings settings() {
            return settings;
        }

        public void refresh() {
            // Mock implementation
        }

        public void createIndexIfNothing() {
            // Mock implementation
        }

        public String getIndex() {
            return "fess.suggest";
        }

        public long getAllWordsNum() {

        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(), "AnalyzerNormalizerTest");
        suggester.createIndexIfNothing();
    }

    @Test
    public void test_constructor() throws Exception {
        AnalyzerNormalizer normalizer = new AnalyzerNormalizer(runner.client(), suggester.settings());
        assertNotNull(normalizer);

        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();

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

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

        SuggestResponse response = suggester.suggest().setQuery("test").execute().getResponse();