If you try to install Symfony 5 (full) and Codeception in standard way by running composer commands like below:
composer create-project symfony/website-skeleton PROJECT_NAME; composer require codeception/codeception;
After running a second line you'll probably get the following error:
Your requirements could not be resolved to an installable set of packages. Problem 1 - codeception/codeception 3.1.2 requires symfony/finder >=2.7 <5.0 -> no matching package found. - codeception/codeception 3.1.1 requires symfony/finder >=2.7 <5.0 -> no matching package found. - codeception/codeception 3.1.0 requires symfony/finder >=2.7 <5.0 -> no matching package found. - Installation request for codeception/codeception ^3.1 -> satisfiable by codeception/codeception[3.1.0, 3.1.1, 3.1.2]. Potential causes: - A typo in the package name - The package is not available in a stable-enough version according to your minimum-stability setting see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details. - It's a private package and you forgot to add a custom repository to find it Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems. Installation failed, reverting ./composer.json to its original content.
We need to either use Codeception >= 4.0 or Symfony < 5.0, because for now Codeception doesn't work with Symfony5