[Tests] Polyfills not loaded

[IonBazan]

When running the test suite on my local environment (PHP 8.1), the polyfill is not loaded correctly, causing the new functions to be not registered. Interestingly, the test is marked as skipped, instead of error/warning 🤔

I bet it has something to do with the custom test runner/hooks but not sure what's wrong there.

vendor/bin/simple-phpunit --filter php83 -vvv
PHPUnit 9.5.26 by Sebastian Bergmann and contributors.

Runtime:       PHP 8.1.14
Configuration: /Users/ionbazan/work/polyfill/phpunit.xml.dist
Warning:       Your XML configuration validates against a deprecated schema.
Suggestion:    Migrate your XML configuration using "--migrate-configuration"!

Testing
SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS                        42 / 42 (100%)

Time: 00:00.317, Memory: 74.00 MB

There were 42 skipped tests:

1) Symfony\Polyfill\Tests\Php83\Php83Test::testJsonValidate with data set #0 (false, '', 'Syntax error')
Internal function not found: json_validate

/Users/ionbazan/work/polyfill/tests/Php83/Php83Test.php:24

2) Symfony\Polyfill\Tests\Php83\Php83Test::testJsonValidate with data set #1 (false, '.', 'Syntax error')
Internal function not found: json_validate

/Users/ionbazan/work/polyfill/tests/Php83/Php83Test.php:24

[...]

[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 ?