pkg/
  __init__.py
  components/
    core.py
    __init__.py
  tests/
    core_test.py
    __init__.py

from ..components.core import GameLoopEvents

tests$ python core_test.py 
Traceback (most recent call last):
  File "core_test.py", line 3, in <module>
    from ..components.core import GameLoopEvents
ValueError: Attempted relative import in non-package