function test_errors()
 {
     $tests = array('"');
     foreach ($tests as $test_str) {
         $conv = new BooleanQueryRewriter();
         $actual = $conv->convert($test_str);
         $this->assertFalse($conv->error_message == '');
     }
 }
 function _expand_fulltext($fields, $relation, $subject)
 {
     $conv = new BooleanQueryRewriter();
     $result = 'MATCH(' . $fields . ') AGAINST(' . "'" . $conv->convert($subject) . "'" . ' IN BOOLEAN MODE)';
     if ($conv->error_message != '') {
         return $this->_set_error($conv->error_message);
     } else {
         return $result;
     }
 }