How to testing code modules?

I created an authentication library for CI4 as code module, now i would like to unit testing the module. But the documentation does not provide guidelines for unit testing for libraries. For unit testing for code modules, there is no guide at all.

My application structure:

application

auth
--MyAuth

----Config

------MyAuth_config.php

----Controllers

------MyAuth_ctrl.php

----Helpers

----Language

------en

--------MyAuth_lang.php

----Libraries

------MyAuth.php

public

system

tests

--system

--_support

--auth <-- I would like to write tests in this folder

vendor

writable