Set up a Symfony2 FomType unit test with the ```ValidatorExtension``` loaded using the ```TypeTestCase``` class

ValidatableTypeTest.php

<?php
/**
 * ValidatableTypeTest.php
 * 
 * @filesource
 */
namespace Acme\DemoBundle\Test\Base;

use Symfony\Component\Form\Extension\Core\CoreExtension;
use Symfony\Component\Form\Extension\Validator\ValidatorExtension;
use Symfony\Component\Form\Tests\Extension\Core\Type\TypeTestCase;

use Symfony\Component\Validator\Mapping\ClassMetadata;

/**
 * Class ValidatableTypeTest
 *
 * @package Acme\DemoBundle\Test\Base
 */
class ValidatableTypeTest extends TypeTestCase
{
    /**
     * @var \PHPUnit_Framework_MockObject_MockObject
     */
    public
        $validator,
        $metadataFactory;

    /**
     * @var \Symfony\Component\Validator\Mapping\ClassMetadata
     */
    public $metadata;

    /**
     * {@inheritDoc}
     */
    protected function setUp()
    {
        $this->metadata        = new ClassMetadata('Symfony\Component\Form\Form');
        $this->validator       = $this->getMock('Symfony\Component\Validator\ValidatorInterface');
        $this->metadataFactory = $this->getMock('Symfony\Component\Validator\MetadataFactoryInterface');

        $this->setValidatorExpectations();

        parent::setUp();
    }

    /**
     * Will be used in the parent class to set up the extensions with the builder
     */
    protected function getExtensions()
    {
        return array(
            new CoreExtension(),
            new ValidatorExtension($this->validator),
        );
    }

    /**
     * Sets up the required expectations for the mocks
     */
    private function setValidatorExpectations()
    {
        $this->validator
            ->expects($this->any())
            ->method('getMetadataFactory')
            ->will($this->returnValue($this->metadataFactory))
        ;

        $this->metadataFactory
            ->expects($this->any())
            ->method('getMetadataFor')
            ->will($this->returnValue($this->metadata))
        ;
    }
}