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:_JetBrainsPyCharm 2016.2.2helperspycharmutrunner.py" C:pathtoMopytest_bashtest_boshtest_bsa_files.py true
I get:
Traceback (most recent call last): File "C:_JetBrainsPyCharm 2016.2.2helperspycharmutrunner.py", line 124, in <module> modules = [loadSource(a[0])] File "C:_JetBrainsPyCharm 2016.2.2helperspycharmutrunner.py", line 43, in loadSource module = imp.load_source(moduleName, fileName) File "C:Dropboxeclipse_workspacespythonwrye-bashMopytest_bashtest_boshtest_bsa_files.py", line 4, in <module> import bosh File "C:Dropboxeclipse_workspacespythonwrye-bashMopybashbosh__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:_Python27python.exe "C:_JetBrainsPyCharm 2016.2.2helperspycharmutrunner.py" C:Dropboxeclipse_workspacespythonwrye-bashMopytest_bashtest_boshtest_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:Dropboxeclipse_workspacespythonwrye-bashMopytest_bashtest_boshtest_bsa_files.py true Process finished with exit code 2
This usage message is from the main() in bash.
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Answer
TLDR: Do
import bash.bosh
or
from bash import bosh
Avoid modifying sys.path
, as this duplicates modules.
When you do
import bosh
it will import the module bosh
. This means Mopy/bash
is in your sys.path
, python finds the file bosh
there, and imports it. The module is now globally known by the name bosh
. Whether bosh
is itself a module or package doesn’t matter for this, it only changes whether bosh.py
or bosh/__init__.py
is used.
Now, when bosh
tries to do
from .. import bass
this is not a file system operation (“one directory up, file bass”) but a module name operation. It means “one package level up, module bass”. bosh
wasn’t imported from its package, but on its own, though. So going up one package is not possible – you end up at the package ''
, which is not valid.
Let’s look at what happens when you do
import bash.bosh
instead. First, the package bash
is imported. Then, bosh
is imported as a module of that package – it is globally know as bash.bosh
, even if you used from bash import bosh
.
When bosh
does
from .. import bass
that one works now: going one level up from bash.bosh
gets you to bash
. From there, bass
is imported as bash.bass
.