There are two files with a chain of commands and a dict that dynamically collects all non-abstract commands.

logic.py

from abc import ABC, abstractmethod

class Command(ABC):
    def __init__(self):
        ...
    
    @abstractmethod
    def run():
        ...

class Commands(dict):
    def __init__(self):
        import comm
        breakpoint()
        for cls in Command.__subclasses__():
            names = self.split_camel_case(cls.__name__)
            self[names] = cls

comm.py

from logic import Command

class TestCommand(Command):
    ...

Debugger output

> logic.py(28) __init__()
  -> for cls in Command.__subclasses__():

(Pdb) comm.TestCommand.__mro__
(<class 'comm.TestCommand'>, <class 'logic.Command'>, <class 'abc.ABC'>, <class 'object'>)

(Pdb) Command.__subclasses__()
[]

By the time the Commands.__init__() is called the base class Command is already defined. The module comm is imported and the subclass TestCommand is defined too. But the list returned by Command.__subclass__() is empty.

Tell me please, what am I missing?