symfony 1.2のsfTesterResponseクラスを日本語に対応させる

<?php
$browser->check('/', 'テスト')->
    with('response')->matches('/\w+の日記/u');

<?php

class myTesterResponse extends sfTesterResponse
{
    public function contains($text)
    {
        $this->tester->like(
            $this->getContent(),
            '/' . preg_quote($text, '/') . '/u',
            sprintf('response contains "%s"', mb_substr($text, 0, 40))
        );

        return $this->getObjectToReturn();
    }

    public function matches($regex)
    {
        if ($regex{0} == '!') {
            $this->tester->unlike(
                $this->getContent(),
                mb_substr($regex, 1),
                sprintf('response content does not match regex "%s"', mb_substr($regex, 1))
            );
        } else {
            $this->tester->like(
                $this->getContent(),
                $regex,
                sprintf('response content matches regex "%s"', $regex)
            );
        }

        return $this->getObjectToReturn();
    }

    protected function getContent()
    {
        $charset = $this->response->getCharset();
        $content = $this->response->getContent();

        if ($charset !== null && strtolower($charset) !== 'utf-8') {
            $content = mb_convert_encoding($content, 'UTF-8', $charset);
        }

        return $content;
    }
}