Multi tool use

Python imports for testing modules with additional dependencies

I want to have my tests in a separate folder from my package code, such that from the top level directory of my project I can run python sample/run.py or python tests/test_run.py, and have both of them resolve all the imports properly.

python sample/run.py

python tests/test_run.py

My directory structure looks like this:

sample/
__init__.py
helper.py
run.py
tests/
context.py
test_run.py


I know there are supposedly many ways to achieve this, as discussed here: Python imports for tests using nose - what is best practice for imports of modules above current package

However, when I try to run python tests/test_run.py, I get a ModuleNotFoundError for 'helper', because 'sample/run.py' imports 'sample/helper.py'.

python tests/test_run.py

In particular, I am trying to follow the convention (suggested in the Hitchhiker's Guide to Python) of explicitly modifying the path using:

import os, sys
sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))


As a result, I have a blank sample/__init__.py, along with the following code files.

sample/__init__.py

sample/run.py:

from helper import helper_fn
def run():
helper_fn(5)
return 'foo'
if __name__ == '__main__':
run()


sample/helper.py:

def helper_fn(N):
print(list(range(N)))


tests/context.py:

import os, sys
sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))

import sample


tests/test_run.py:

from context import sample
from sample import run

assert run.run() == 'foo'


So I have two questions:

sample/run.py

tests/test_run.py

1 Answer
1

Edited:

To make both sample/run.py and tests/test_run.py work, you should add the path of sample directory into python path. So, your tests/context.py should be

sample/run.py

tests/test_run.py

sample

tests/context.py

import os, sys
sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))
sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '../sample')))


import sample


This change will let Python know the path of helper module.

helper

sample/run.py should be:

sample/run.py

from .helper import helper_fn
def run():
helper_fn(5)
return 'foo'
if __name__ == '__main__':
run()


Implicit relative imports within packages are not available in Python 3. Please check below:

The import system has been updated to fully implement the second phase of PEP 302. There is no longer any implicit import machinery - the full import system is exposed through sys.meta_path. In addition, native namespace package support has been implemented (see PEP 420). link

This documentation might be helpful to understand Intra-Package-References.

tests/test_run.py

ModuleNotFoundError: No module named '__main__.helper'; '__main__' is not a package

sample/run.py

if __name__ == 'main': run()

sample/main.py

from run import run

from .helper ...

tests/test_run.py

sample/main.py

from helper ...

sample/main.py

tests/test_run.py

python -m sample.run

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