Deprecate configuring caches through DoctrineCacheBundle

[alcaeus]

With this PR, we are deprecating configuring cache drivers for ORM through DoctrineCacheBundle, as the bundle is deprecated (see doctrine/DoctrineCacheBundle#156). Instead of assuming array as default, the bundle now uses an appropriate cache pool (app or system depending on the cache in question) if no explicit configuration was given. This avoids deprecation notices for people that did not add any cache configuration.

Caches should either be configured by passing a symfony/cache pool or service ID. The latter allows using doctrine/cache classes, but without the comfort of configuring the caches through bundle config. The implicit requirement on doctrine/cache-bundle will be removed in DoctrineBundle 2.0.

[alcaeus]

Coverage tests are broken because of a deprecation:

1x: The "Symfony\Component\HttpKernel\EventListener\TranslatorListener" class is deprecated since Symfony 4.3 and will be removed in 5.0, use LocaleAwareListener instead.
    1x in ImportMappingDoctrineCommandTest::setup from Doctrine\Bundle\DoctrineBundle\Tests\Command

Can't figure out what's using it though, especially since this doesn't happen in any of the other builds. Could this be a problem because of the code coverage whitelist?

Edit: also can't reproduce the failure locally 🤷‍♂️

[SenseException]

The service of the event-subscriber is called depending on some configuration.

https://github.com/symfony/framework-bundle/blob/v4.3.1/DependencyInjection/FrameworkExtension.php#L1085

It seems to depend on !$this->isConfigEnabled($container, $config) above. Can you confirm that? Is there an enabled or disabled translator?

[alcaeus]

Turns out the reason for the failure was that the coverage tests installed symfony/messenger in version 4.2. This also locks the FrameworkBundle to 4.2, which still uses the now deprecated class. Locally, I had symfony/messenger 4.3 installed, which doesn't cause the issue. I've fixed .travis.yml in #983 which will be merged up soon.

[stof]

the rule for marked a test as @group legacy (and so allowing it to use the BC layer to test it) is that this test gets removed when removing the corresponding deprecated feature (or converted to a test expected an exception, if the deprecation is meant to be replaced by an exception forbidding a given case). Many tests here should be adapted to keep covering different parts of the bundle without using deprecated APIs.

[alcaeus]

@stof you're right - I didn't think of those. I've updated the test and included some legacy tests to test existing functionality. There may be a few more changes necessary once we drop old stuff, but that's alright.