fix: identify already tracked resources by ID AND type

[elfin-sbreuers]

Fixes a bug in JSON:API serialization where resources with the same numeric ID but different types were incorrectly considered duplicates.
Now, the type is combined with the id to uniquely identify each included resource, ensuring all distinct entities appear in the included section.

[soyuka]

Quite nice, if you could add a test it'd be awesome

[elfin-sbreuers]

I want to help protect this fix with a regression test, but I don’t see any JSON:API tests in the suite I could build on. I’m happy to work on adding one — just looking for guidance on where it would fit best and how to start with it.

[soyuka]

tests/Functional/JsonApiTest.php for example
there's also a test failure that looks related I think we need to update the behat test (or you can remove that test from behat and reproduce it into phpunit)

[elfin-sbreuers]

Thanks for the pointers! I took a look at tests/Functional/JsonApiTest.php. Right now it references a non-existing endpoint and doesn’t include concrete data assertions, so what I need is more of a starting template. I’d appreciate some guidance on setting up a realistic URL and test data structure to properly assert expected return values.

Regarding the Behat test, I’m not sure where to begin. I’m comfortable with JSON:API and Symfony (which is how I identified the underlying issue and fix), but I’d value some pointers on how best to integrate or update the test.