Add #[RunTestsInSeparateProcesses] attribute to all Kernel and Functional tests

Attached file is the Rector config file (rector.php) that conveniently has a Rule class to do what is in the MR.

To run this:

• install rector via composer require -dev rector/rector
• run rector with the config file via vendor/bin/rector
• run PHPCBF via vendor/bin/phpcbf --filter=GitModified --standard=SlevomatCodingStandard --sniffs=SlevomatCodingStandard.Namespaces.AlphabeticallySortedUses core (this reorders alphabetically the use imports for cleanliness
• your diff will be what to put in the MR

So, chicken and egg - we can't do this until we have PHPUnit 10 in place, otherwise PHPStan complains about the fact that the attribute class does not exist.

I bet it will affect split of tests for running in parallel to optimize pipeline

Uploading latest version of the rector script

Only manual changes:

• one addition to PHPStan ignoreErrors, to be removed once PHPUnit 10 is in
• fixes for two functional tests that were hardcoding the line number of their scripts in a check

As noted over in #3417066-120: Upgrade PHPUnit to 10, drop Symfony PHPUnit-bridge dependency → , we can't mix PHPUnit attributes and annotations, we will have to convert them all at once.

mondrake → closed merge request !7914

I'm afraid we have to reopen this is light of PHPUnit 12 - that is making final the constructor of TestCase. We can no longer override it to set programmatically at the base class level.

The issue was reported upstream but no alternatives were suggested: https://github.com/issues/created?issue=sebastianbergmann%7Cphpunit%7C5838

So I think we need to

• add the #[RunTestsInSeparateProcesses] attribute to all existing kernel and functional tests
• add a PHPStan rule that will prevent new kernel and functional tests to miss the attribute

We need to convert all tests from annotation to attributes, first.