[Tests] Polyfills not loaded about polyfill

[nicolas-grekas]

That's how it's supposed to work to me: the internal function (the native one, non-polyfilled) is not found since you're on PHP 8.1
Try running this on PHP 8.3, it should be green.

[IonBazan]

That doesn't make much sense to me. From what I remember, we were including bootstrap.php files using TestListenerTrait which made sure the function is registered globally - this is to use same test code on PHP 8.1 and 8.3 and compare results between polyfilled and native implementation.

[IonBazan]

OK, I think I got it now - I always thought we run the future-compatible tests on old versions too, and that the functions are globally registered but now I see the mechanism is much more sophisticated. I just wonder if that won't produce any regressions, as we test json_validate only on PHP 8.3 and up, we could technically put some new syntax which is not compatible with older versions and still observe a green CI 🤔

[stof]

Aren't we testing the polyfill variant on all PHP versions ?