assertNull(facetInfo.sort);
        assertNull(facetInfo.missing);
    }

    // Test init with duplicate and empty field names
    @Test
    public void test_init_withDuplicateAndEmptyFieldNames() {
        FessConfig fessConfig = new FessConfig.SimpleImpl() {
            @Override
            public String getQueryFacetFields() {
                return "field1, field2, field1, , field3, field2";