[Form] Fix "Adding custom extensions" section

[webmozart]

Currently, the section "Adding custom extensions" in http://symfony.com/doc/current/cookbook/form/unit_testing.html#adding-custom-extensions is overly complicated. The same result as in the code on that page can be achieved with:

use Symfony\Component\Form\PreloadedExtension;

class TestedTypeTest extends TypeTestCase
{
    protected function getExtensions()
    {
        $validator = $this->getMock('\Symfony\Component\Validator\Validator\ValidatorInterface');
        $validator->method('validate')->will($this->returnValue(new ConstraintViolationList()));

        $typeGuesser = $this->getMockBuilder('Symfony\Component\Form\Extension\Validator\ValidatorTypeGuesser')
            ->disableOriginalConstructor()
            ->getMock();

        return array(
            new PreloadedExtension(
                // Form types
                array(),
                // Form type extensions
                array(new FormTypeValidatorExtension($validator)),
                // Type guesser
                $typeGuesser
            ),
        );
    }

    // ... your tests
}

[stof]

And for the case of the validator, it can even be simpler with the ValidatorExtension instead of using the PreloadedExtension and registering the different things manually (in latest versions, the ButtonTypeValidatorExtension might be needed too for instance)

[soullivaneuh]

@stof an code example could be appreciated. :-) 👍

[stof]

use Symfony\Component\Form\Extension\Validator\ValidatorExtension;

class TestedTypeTest extends TypeTestCase
{
    protected function getExtensions()
    {
        $validator = $this->getMock('\Symfony\Component\Validator\Validator\ValidatorInterface');
        $validator->method('validate')->will($this->returnValue(new ConstraintViolationList()));

        return array(
            new ValidatorExtension($validator),
        );
    }

    // ... your tests
}