Test case for testing database queries, based on WebTestCase, doctrine tasks and using LoaderService.php (browse https://gist.github.com/devhelp for it)

DbTestCase.php

<?php

namespace Devhelp\Bundle\TestBundle\Test;

use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
use Doctrine\DBAL\DriverManager;
use Doctrine\ORM\Tools\SchemaTool;

/**
 * @package devhelp/test-bundle
 * @author Paweł Barański <pawel.baranski1@gmail.com>
 */
class DbTestCase extends WebTestCase
{
    protected function setUp()
    {
        static::$kernel = static::createKernel();
        static::$kernel->boot();
        $this->dropDatabase();
        $this->createDatabase();
        //this may be overkill, but without shutdown/boot it does not work
        //simpliest solution, as said - may not be most optimal
        static::$kernel->shutdown();
        static::$kernel->boot();
        $this->updateSchema();
    }
    
    protected function getDoctrineConnection($name = null)
    {
        return $this->getContainer()->get('doctrine')->getConnection($name);
    }
    
    protected function getEntityManager()
    {
        return $this->getContainer()->get('doctrine')->getEntityManager();
    }
    
    protected function dropDatabase()
    {
        $connection = $this->getDoctrineConnection();

        $params = $connection->getParams();

        $name = isset($params['path']) ? $params['path'] : (isset($params['dbname']) ? $params['dbname'] : false);

        if (!isset($params['path'])) {
            $name = $connection->getDatabasePlatform()->quoteSingleIdentifier($name);
        }
        
        if (!$name) {
            throw new \InvalidArgumentException("Connection does not contain a 'path' or 'dbname' parameter and cannot be dropped.");
        }
        try {
            $connection->getSchemaManager()->dropDatabase($name);
        } catch(\Exception $e) {}        
    }
    
    protected function createDatabase()
    {
        $connection = $this->getDoctrineConnection();

        $params = $connection->getParams();
        $name = isset($params['path']) ? $params['path'] : $params['dbname'];

        unset($params['dbname']);

        $tmpConnection = DriverManager::getConnection($params);

        // Only quote if we don't have a path
        if (!isset($params['path'])) {
            $name = $tmpConnection->getDatabasePlatform()->quoteSingleIdentifier($name);
        }

        $tmpConnection->getSchemaManager()->createDatabase($name);
        
        $tmpConnection->close();
    }
    
    protected function updateSchema()
    {
        $em = $this->getEntityManager();

        $metadatas = $em->getMetadataFactory()->getAllMetadata();

        if (!empty($metadatas)) {
            $schemaTool = new SchemaTool($em);

            $schemaTool->updateSchema($metadatas, true);
        }        
    }

    /**
     * @return \Symfony\Component\DependencyInjection\ContainerInterface
     */
    protected function getContainer()
    {
        return static::$kernel->getContainer();
    }
    
    /**
     * @return Devhelp\Bundle\DataFixturesBundle\Service\LoaderService
     */
    protected function getFixturesLoader()
    {
        return $this->getContainer()->get('devhelp.data_fixtures.loader');
    }
}

ExampleDbTest.php

<?php

namespace Devhelp\Bundle\DemoBundle\Tests;

use Devhelp\Bundle\TestBundle\Test\DbTestCase;

/**
 * @package devhelp/demo-bundle
 * @author Paweł Barański <pawel.baranski1@gmail.com>
 */
class DemoEntityRepositoryTest extends DbTestCase
{
    public function testSomeExampleRepositoryMethod()
    {
        $this->getFixturesLoader()->load(__DIR__.'/../DataFixtures/ORM/');
        
        $demoEntityRepository = $this->getEntityManager()->getRepository('DevhelpDemoBundle:DemoEntity');

        $expectedDemoEntity = $demoEntityRepository->findOneBySomeUniqueColumnName('some-unique-column-value');
        $actualDemoEntity = $demoEntityRepository->someExampleRepositoryMethod();
        
        $this->assertEquals(
            $expectedDemoEntity->getId(),
            $actualDemoEntity->getId()
        );
    }
}