ApplicationBundle.php

<?php

namespace Company\ApplicationBundle;

use Symfony\Component\HttpKernel\Bundle\Bundle;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Loader\XmlFileLoader;

class ApplicationBundle extends Bundle {
    public function registerExtensions(ContainerBuilder $container) {
        parent::registerExtensions($container);

        // register controllers
        $loader = new XmlFileLoader($container);
        $loader->load(__DIR__.'/Resources/config/controllers.xml');
    }
}

controller_routing.xml

<?xml version="1.0" encoding="UTF-8" ?>

<routes xmlns="http://www.symfony-project.org/schema/routing"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.symfony-project.org/schema/routing http://www.symfony-project.org/schema/routing/routing-1.0.xsd">

    <route id="index" pattern="/index">
        <default key="_controller">index_controller:indexAction</default>
    </route>
</routes>

controller_test_sample.php

<?php
$client = $this->createClient();

$client->request('GET', '/index');
$response = $client->getResponse();

$this->assertEquals(200, $response->getStatusCode());
$this->assertRegExp('/<h1>My Cool Website<\/h1>/', $response->getContent());

controllers.xml

<?xml version="1.0" ?>

<container xmlns="http://www.symfony-project.org/schema/dic/services"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.symfony-project.org/schema/dic/services http://www.symfony-project.org/schema/dic/services/services-1.0.xsd">

    <services>
        <service id="index_controller" class="Company\ApplicationBundle\Controller\IndexController">
            <call method="setTemplating" />
                <argument type="service" id="templating" />
            </call>
        </service>
    </services>
</container>

directories

Company
| - ApplicationBundle
|   | - Controller
|   |   | - IndexController.php
|   | - Resources
|   |   | - config
|   |   |   | - controller_routing.xml
|   |   |   | - controllers.xml
|   |   | - views
|   |   |   | - Index
|   |   |   |    | - index.php
|   | - ApplicationBundle.php

IndexController.php

<?php

namespace Company\ApplicationBundle\Controller;

use Symfony\Bundle\FrameworkBundle\Templating\Engine;

class IndexController
{
    /**
     * @var Symfony\Bundle\FrameworkBundle\Templating\Engine
     */
    private $templating;

    /**
     * @param Symfony\Bundle\FrameworkBundle\Templating\Engine $templating
     */
    public function setTemplating(Engine $templating)
    {
        $this->templating = $templating;
    }

    /**
     * @return Symfony\Component\HttpFoundation\Response
     */
    public function indexAction()
    {
        return $this->templating->render('ApplicationBundle:Index:index');
    }
}

IndexControllerTest.php

<?php

namespace Company\ApplicationBundle\Tests\Controller;

use Company\ApplicationBundle\Controller\IndexController;

class IndexControllerTest extends \PHPUnit_Framework_TestCase
{
    //...
    public function testIndexAction()
    {
        $templating = $this->getMockTemplating();
        $templating->expects($this->once())
            ->method('render')
            ->with('ApplicationBundle:Index:index')
            ->will($this->returnValue('success'))
        ;

        $controller = new IndexController();
        $controller->setTemplating($templating);

        $this->assertEquals('success', $controller->indexAction());
    }

    private function getMockTemplating()
    {
        return $this->getMock('Symfony\Bundle\FrameworkBundle\Templating\Engine', array(), array(), '', false, false);
    }

}