Python 3.9 Tests in separate directory - Module not found

I am working on my first python project, and I would like to structure the folders correctly. What I have so far is :

HomeDir/MyProject/
        ConfigHandler.py
HomeDir/Tests/
        ConfigHanderTests.py

In the ConfigHanderTests.py I am importing a module defined in ConfigHandler.py called ConfigHandler :

from ConfigHandler import ConfigHandler

But when I run the tests using :

python -m unittest ConfigHandlerTests

I get the following error :

ModuleNotFoundError: No module named 'ConfigHandler'

I have read that I need an init.py in the test folder? But other posts mention that is no longer required. If I just have all the python files and test files in one directory, it works fine. But splitting out into folders doesn't work. What am I missing?

Thanks!