Ensure PHP assertions are enabled in test environments

Please credit @wim leers for contributing to the discovery and suggested fix for this issue.

This might not be necessary if we fix in core via 📌 Remove mentions of assert.active from .htaccess Needs work , although existing tests against current versions of core are running with no assertions so we might still want to fix that.

fjgarlin → credited wim leers → .

Thanks for the proposed fix. Maybe we could add a settings.local.php file instead? We are using core's htaccess so we'd need to manipulate it.

It might equally work by adding

ini_set('zend.assertions', 1);
ini_set('assert.active', 1);

to settings.local.php, but needs testing. zend.assertions cannot be set to 1 if it was -1 in php.ini, but as we control the environment that will never be the case here.