ValidatorInterface::validate($formType) stopped working with symfony/form:4.2.3

[Loupax]

Symfony version(s) affected: 4.2.*

Description
After updating the form component to version 4.2.3, the method ValidatorInterface::validate($formType) stopped returning any violations when it contains an invalid value object.

How to reproduce
This is the common code between the two versions
https://github.com/Loupax/broken_validation/blob/master/src/Controller/DefaultController.php
Please note how we don't actually submit the form. This is done on purpose.

You can switch between the following branches for a working an broken example
https://github.com/Loupax/broken_validation/blob/working_example/composer.json#L14
https://github.com/Loupax/broken_validation/blob/broken_example/composer.json#L14

[xabbuh]

The previous behaviour was a bug that was fixed in #30265 (see the many referenced bug reports there for more details). I don't think there is anything we can do about it.

Maybe you can describe your use case and we can think about alternative solutions to your problem.

[Loupax]

This came up because I keep my validation constraints inside my form types and came up with a case where I need to validate my data without having an HTTP request at hand.

As long as that's expected behavior, I'll try calling $form->submit() for my data and keep working from there

[xabbuh]

For that use case I would probably rather move the constraints to your underlying model because that's the data you seem to want to validate. Validating a form only makes sense if there are submitted data (and then I would only add constraints to form fields that are not mapped to the model).

[Loupax]

Closing since this is confirmed not to be a bug