A piece of code which needs to be tested!

    public function write($sessionId, $sessionData)
    {
            $sth = $this->databaseConnection->prepare("INSERT INTO `{$this->DBTableName}` (`session_id`,`session_name`,`session_data`) VALUES(:session_id, :session_name, :session_data) ON DUPLICATE KEY UPDATE `session_data`=:session_data;");
            $sth->bindValue(':session_id', $sessionId);
            $sth->bindValue(':session_name', $this->sessionName);
            $sth->bindValue(':session_data', $sessionData);
            return $sth->execute();
    }