Problem with Project-tests

The tests folder that comes in the *root* of the CodeIgniter AppStarter and DevStarter (and manual installations from repo clone) is designed to test the framework itself. If you are planning on working on the framework, submitting PRs, bug reports, etc, then you should use that. If you are writing an app that uses the framework you can assume that the framework is passing its own tests and you do not need the tests folder (a copy is always available in vendor for Composer installs) - instead you want tests specific to your project, hence "ProjectTests". You will definitely have problems if you try to keep the framework tests in your root and add or merge ProjectTests - the two are set up very differently.