<?php

use Behat\Mink\Mink,
    Behat\Mink\Session,
    Behat\Mink\Driver\SeleniumDriver;

use Selenium\Client as SeleniumClient;

$startUrl = 'http://example.com';

$mink = new Mink(array(
    'selenium' => new Session(new SeleniumDriver(new SeleniumClient($host, $port))),
));

$mink->getSession('selenium')->getPage()->findLink('Chat')->click();