Obviously not a bug. Please elaborate your use-case.

As explained also in the ODM issue:

It is mostly used for testing actually: I'm using a DocumentManager with a mocked connection and a custom metadata factory in order to precisely control what is returned from the factory itself

I used this feature in 2.x without any problem, but defining the concrete type into the EntityManager does not allow to use any other class implementing the common interface/extending the abstract class.

You did not answer the question.

You did not answer the question.

Yes, I did. My use-case is to create a fake/mock version of the class metadata factory implementing Doctrine\Persistence\Mapping\ClassMetadataFactory interface, and using it in testing to control what is returned from the factory itself and when the factory methods are called.

In the current state calling setClassMetadataFactoryName on configuration with such a class results in a fatal error on entity manager construction. But the same thing was possible in 2.x because the property type was not defined, so it was possible to implement the interface/extend the abstract class to have your custom implementation of the class metadata factory.

What else do you need to know precisely?

As far as I know, our factory is not final, so you may still mock it.

The class itself is not final, but some of the public methods are final in ClassMetadataFactory and in AbstractClassMetadataFactory and cannot be overridden (also what's the purpose of the abstract class if cannot be used in the entity manager?) .

I'm currently replacing the class completely, just implementing the interface.

I see. Well, we could introduce a new interface for our factory that you can mock. Please send a PR.

👍 Ok, thanks. I'll send it tomorrow.

I was wondering about the interface introduced in #11497. It seems that it contains the rest of the public methods that were added to the Doctrine\ORM\Mapping\ClassMetadataFactory as the "rest" that isn't provided by Doctrine Persistence. There is getOwningSide(), a setter for an EntityManager and a Cache setter for Psr\Cache\CacheItemPoolInterface instances. These seem to be different responsibilities for just putting then into one interface. Setting a Cache happens in Persistence while the EntityManager is in ORM. I wonder if those can be split up so that ORM doesn't get an interface where everything else is put into.

@SenseException I agree with your objections, but the same applies to the ClassMetadataFactory class.

The meaning of that interface is to create a minimum set of methods used by the ORM that needs to be implemented in order to override the metadata factory.

I don't know if this could be split easily; maybe the setters could be avoided passing them to the factory constructor, but in this case you can't just customise the factory class name in configuration, but you need to set into the configuration object at least a closure that creates the factory.