python - relative path not working even with __init__.py

I know that there are plenty of similar questions on . But the common answer doesn't seem to be working for me.

I have a file structure like this

  proj/
       lib/
          __init__.py
          aa.py

          bb.py
          test/
               __init__.py
               aa_test.py

I figured that if I include the code in my test.py

import lib.aa

or

from lib import aa

I would be able to reference the modules in the lib/ directory. But that did not work.

So I tried to add to path, and it adds it correctly:

os.environ["PATH"] += ":%s" % os.path.abspath(os.path.join("..",""))
print os.environ["PATH"]

but even now when I try the import statements above... I keep getting the error

ImportError: No module named aa

or

ImportError: Importing from non-package 

Is there something obvious I am missing?

Is there a way to check if I have configured my __init__.py files correctly, or to see my package hierarchy?

Answer

You need to update your sys.path, which is where python looks for modules, as opposed to your system's path in the current environment, which is what os.environ["PATH"] is referring to.

Example:

import os, sys
sys.path.insert(0, os.path.abspath(".."))
import aa

After doing this, you can use your functions in aa like this: aa.myfunc()

There's some more information in the accepted answer for python: import a module from a directory