[8.x] Fix Doctrine type mappings creating too many connections

[bakerkretzmar]

TLDR: this PR closes #40297 by only registering custom Doctrine type mappings on a Doctrine connection after that connection is created (as opposed to creating one to register them).

Context

My and @TomHAnderson's original PR, #40119, created an issue with tests where way too many database connections would be created. We were manually creating a database connection to register the custom type mappings, which caused database connections to be created every time the app boots, and dozens of unnecessary connections to be created when tests are run in parallel.

I'm still not entirely sure why all those connections stick around, I tried manually closing/destroying them through Doctrine and that didn't seem to work.

[bakerkretzmar]

@canvural @skollro if either of you have feedback about this or are able to test it that would be greatly appreciated 🙏🏻

[canvural]

@bakerkretzmar I confirm this fixes it! Thank you! Couldn't test with parallel though.

[skollro]

@bakerkretzmar I've just tried your proposed solution.
Registering a custom type via database.dbal.types works in sequential and parallel tests now.
DB::registerDoctrineType() in the AppServiceProvider's register method works for sequential tests, but not for parallel tests.

[bakerkretzmar]

DB::registerDoctrineType() in the AppServiceProvider's register method works for sequential tests, but not for parallel tests.

@skollro does it work if you do it in the boot method?

[skollro]

@bakerkretzmar unfortunately, no. It seems like getDoctrineConnection isn't even called in parallel test environments 🤔

[bakerkretzmar]

@skollro thanks. It does get called but not where I thought it did, working on fixing this now.

[bakerkretzmar]

I've kept this whole registerDoctrineType method for backwards compatibility but it can be removed in Laravel 9 because the same method on the DatabaseManager class replaces it. I'll PR that today too.

[bakerkretzmar]

I'm pretty sure this fixes the issue now in all the cases mentioned here and in various comments: registering custom types either via database.dbal.types or with DB::registerDoctrineType() in a service provider, and testing either normally or in parallel.

There is some code duplication here to maintain complete backwards compatibility, I'll submit another PR asap to clean this up a bit for Laravel 9. Basically, the type registration has to happen through the DatabaseManager so that it persists across test runs properly in parallel testing, but every single new connection that gets created also has to be provided with the types. If there's a better way to do that than to store them in an array, I'm all ears 😅

[driesvints]

Thanks @bakerkretzmar & @TomHAnderson !

[skollro]

Thanks! Can confirm DB::registerDoctrineType() and database.dbal.types also works with parallel testing now.
But the backwards-compatible DB::connection()->registerDoctrineType() still breaks parallel tests.

[bakerkretzmar]

Yeah I'm going to remove DB::connection()->registerDoctrineType() if possible.