[Python] Attempted relative import beyond toplevel package

Here is my folder structure:

Mopy/ # no init.py !
bash/
__init__.py
bash.py # <--- Edit: yep there is such a module too
bass.py
bosh/
__init__.py # contains from .. import bass
bsa_files.py
...
test_bash\
__init__.py # code below
test_bosh\
__init__.py
test_bsa_files.py


In test_bash\__init__.py I have:

import sys
from os.path import dirname, abspath, join, sep
mopy = dirname(dirname(abspath(__file__)))
assert mopy.split(sep)[-1].lower() == 'mopy'
sys.path.append(mopy)
print 'Mopy folder appended to path: ', mopy


while in test_bsa_files.py:

import unittest
from unittest import TestCase

import bosh

class TestBSAHeader(TestCase):
def test_read_header(self):
bosh.bsa_files.Header.read_header()

if __name__ == '__main__':
unittest.main()


Now when I issue:

python.exe "C:\_\JetBrains\PyCharm 2016.2.2\helpers\pycharm\utrunner.py" C:\path\to\Mopy\test_bash\test_bosh\test_bsa_files.py true


I get:

Traceback (most recent call last):
File "C:\_\JetBrains\PyCharm 2016.2.2\helpers\pycharm\utrunner.py", line 124, in <module>
modules = [loadSource(a[0])]
File "C:\_\JetBrains\PyCharm 2016.2.2\helpers\pycharm\utrunner.py", line 43, in loadSource
module = imp.load_source(moduleName, fileName)
File "C:\Dropbox\eclipse_workspaces\python\wrye-bash\Mopy\test_bash\test_bosh\test_bsa_files.py", line 4, in <module>
import bosh
File "C:\Dropbox\eclipse_workspaces\python\wrye-bash\Mopy\bash\bosh\__init__.py", line 50, in <module>
from .. import bass
ValueError: Attempted relative import beyond toplevel package


Since 'Mopy" is in the sys.path and bosh\__init__.py is correctly resolved why it complains about relative import above the top level package ? Which is the top level package ?

Incidentally this is my attempt to add tests to a legacy project - had asked in Python test package layout but was closed as a duplicate of Where do the Python unit tests go?. Comments on my current test package layout are much appreciated !


Well the answer below does not work in my case:

The module bash.py is the entry point to the application containing:

if __name__ == '__main__':
main()


When I use import bash.bosh or from bash import bosh I get:

C:\_\Python27\python.exe "C:\_\JetBrains\PyCharm 2016.2.2\helpers\pycharm\utrunner.py" C:\Dropbox\eclipse_workspaces\python\wrye-bash\Mopy\test_bash\test_bosh\test_bsa_files.py true
Testing started at 3:45 PM ...
usage: utrunner.py [-h] [-o OBLIVIONPATH] [-p PERSONALPATH] [-u USERPATH]
[-l LOCALAPPDATAPATH] [-b] [-r] [-f FILENAME] [-q] [-i]
[-I] [-g GAMENAME] [-d] [-C] [-P] [--no-uac] [--uac]
[--bashmon] [-L LANGUAGE]
utrunner.py: error: unrecognized arguments: C:\Dropbox\eclipse_workspaces\python\wrye-bash\Mopy\test_bash\test_bosh\test_bsa_files.py true

Process finished with exit code 2


This usage message is from the main() in bash.

This is different from the question linked as turns out the reason was partly a clash between modules and package names

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