@Test
    public void test_assistCurrentDBDef() {
        DBDef result = invokerAssistant.assistCurrentDBDef();
        assertNull(result);
    }

    // Test assistDataSource
    @Test
    public void test_assistDataSource() {
        DataSource result = invokerAssistant.assistDataSource();
        assertNull(result);
    }

    // Test assistDBMetaProvider
    @Test
    public void test_assistDBMetaProvider() {

        assertNull(languageHelper.getSupportedLanguage("fr"));
        assertNull(languageHelper.getSupportedLanguage("de"));
        assertNull(languageHelper.getSupportedLanguage("unknown"));
    }

    @Test
    public void test_getSupportedLanguage_blank() {
        assertNull(languageHelper.getSupportedLanguage(null));
        assertNull(languageHelper.getSupportedLanguage(""));

        // These should return null
        assertNull(freshData.getDocumentItems());
        assertNull(freshData.getFacetResponse());
        assertNull(freshData.getAppendHighlightParams());
        assertNull(freshData.getExecTime());
        assertNull(freshData.getAllRecordCountRelation());
        assertNull(freshData.getPageNumberList());
        assertNull(freshData.getSearchQuery());

        String type = null;
        String message = null;
        InvalidAccessTokenException exception = new InvalidAccessTokenException(type, message);

        assertNull(exception.getType());
        assertNull(exception.getMessage());
        assertNull(exception.getCause());
    }

    @Test
    public void test_constructor_withEmptyType() {
        // Test constructor with empty type string
        String type = "";

        // Verify
        assertNotNull(exception);
        assertNull(exception.getMessage());
        assertNull(exception.getCause());
        assertNull(exception.getMessageCode());
    }

    @Test
    public void test_constructor_twoParametersWithNullMessageCode() {
        // Setup
        final String message = "Test message";

        // Execute

        assertNull(exception.getMessage());
        assertNull(exception.getCause());
        assertTrue(exception instanceof FessSystemException);
    }

    @Test
    public void test_constructorWithNullCause() {
        // Test constructor with null cause
        SearchQueryException exception = new SearchQueryException((Throwable) null);

        assertNull(exception.getCause());

        Map<String, Object> map = new HashMap<>();
        map.put("key", null);

        assertNull(MapValueExtractor.getString(map, "key"));
    }

    @Test
    public void testGetString_withMissingKey() {
        Map<String, Object> map = new HashMap<>();

        assertNull(MapValueExtractor.getString(map, "missing"));
    }

    @Test
    public void testGetString_withDefaultValue() {

        // Verify
        assertNotNull(exception);
        assertNull(exception.getMessage());
        assertNull(exception.getCause());
        assertNull(exception.getMessageCode());
    }

    @Test
    public void test_constructor_twoParametersWithNullMessageCode() {
        // Setup
        final String message = "Query error without message code";

                    return null;
                }
                return createMockRescorerBuilder();
            }
        };

        assertNull(queryRescorer.evaluate(Collections.emptyMap()));
        assertNull(queryRescorer.evaluate(new HashMap<>()));
    }

    @Test
    public void test_evaluate_withParams() {
        // Test implementation that returns a RescorerBuilder

    // Test default constructor
    @Test
    public void test_constructor() {
        FacetInfo info = new FacetInfo();
        assertNull(info.field);
        assertNull(info.query);
        assertNull(info.size);
        assertNull(info.minDocCount);
        assertNull(info.sort);
        assertNull(info.missing);
    }

    // Test init method with various configurations
    @Test
    public void test_init_withAllFields() {