Symfony 4 with symfony/flex is incompatible with symfony/symfony. That is why I removed the dependency and re-added only the relevant sub-packages. While on it, I updated other dependencies such as PHPUnit and, consequently, migrated the code as necessary for the new dependencies in order for the tests to still run. This way, the package can now be used by Symfony 4 users too, to automatically generate the HTML5 Cache manifest.
TL;DR:
- upgrade dependencies
- upgrade tests
Posted on Utopian.io - Rewarding Open Source Contributors