protected function assertTableKeys($expected, \OC_DB_StatementWrapper $query, $keyName)
 {
     $result = $query->execute();
     $users = array();
     while ($row = $result->fetchRow()) {
         $users[] = $row[$keyName];
     }
     $users = array_unique($users);
     sort($users);
     sort($expected);
     $this->assertEquals($expected, $users);
 }