fix(FormErrorHandler): add method to FormInterface

[titoko]

Q	A
Bug fix?	yes
New feature?	no
Doc updated	no
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Fixed tickets	#...
License	MIT

Since Symfony 6.1 FormErrorIterator property $form is typehint to FormInterface since https://github.com/symfony/symfony/commit/85065e4f76eb0e75163277498bbc4fadb3ae49f8 .

This PR https://github.com/schmittjoh/serializer/pull/1362 add the possibility to serialize Interface but lead to the following error call_user_func_array(): Argument #1 ($callback) must be a valid callback, class JMS\Serializer\Handler\FormErrorHandler does not have a method "serializeFormInterfaceTojson" ( see also https://github.com/FriendsOfSymfony/FOSRestBundle/pull/2371 )

Adding the method option fix this issue

[scyzoryck]

Hello! Thanks for the contribution! Would it be possible to add some test cases for it, please? Just to make sure that it works for older & new versions.

Best, Marcin.

[titoko]

Well, don't know if the test is really relevant but at least it should avoid regression :) . Tell me if it's enough for you

[scyzoryck]

I think it would be better to check if it is callable - to make sure that it is not dependent on function name :) What do you think about something like:

public function testSerializeFormInterface()
    {
        $registry = new HandlerRegistry([]);
        $registry->registerSubscribingHandler($this->handler);
        $callback = $registry->getHandler(GraphNavigatorInterface::DIRECTION_SERIALIZATION, FormInterface::class, 'json');
        $serialised = $callback($this->visitor, $this->createForm(), []);
        // ...assert result? :) 
    }

It looks like it fails with similar result:

Error: Call to undefined method JMS\Serializer\Handler\FormErrorHandler::serializeFormInterfaceTojson()

[goetas]

done in https://github.com/schmittjoh/serializer/pull/1432