如何设置我的导入以运行我的 python 应用程序而不安装它，并且仍然能够使用诗歌运行 tox？

Question

I have a python 3.6 code-base which needs to be installed in the environment's site-packages directory in order to be called and used. After moving it to docker, I decided that I should set up a shared volume between the docker container and the host machine in order to avoid copying and installing the code on the container and having to rebuild every time I made a change to the code and wanted to run it. In order to achieve this, I had to change a lot of the import statements from relative to absolute. Here is the structure of the application:

-root
  -src
    -app
  -test

In order to run the application from the root directory without installing it, I had to change a lot of the import statements from

from app import something

to:

import src.app.something

The problem is that I use poetry to build the app on an azure build agent, and tox to run the tests. The relevant part of my pyproject.toml file looks like this:

[tool.poetry]
name = "app"
version = "0.1.0"
packages = [{include = 'app', from='src'}]

The relevant part of my tox.ini file looks like this:

[tox]
envlist = py36, bandit, black, flake8, safety
isolated_build = True

[testenv:py36]
deps =
    pytest
    pytest-cov
    pytest-env
    pytest-mock
    fakeredis
commands =
    pytest {posargs} -m "not external_service_required" --junitxml=junit_coverage.xml --cov report=html --cov-report=xml:coverage.xml

I'm not an expert in tox or poetry, but from what I could tell, the problem was that the src directory wasn't being included in the build artifact, only the inner app directory was, so I added a parent directory and changed the directory structure to this:

-root
  -app
    -src
      -app
  -test

And then changed the poetry configuration to the following in order to include the src directory

[tool.poetry]
name = "app"
version = "0.1.0"
packages = [{include = 'src', from='app'}]

Now when I change the imports in the tests from this:

from app import something

to this:

from app.src.app import something 

The import is recognized in Pycharm, but when I try to run tox -r, the I get the following error:

E   ModuleNotFoundError: No module named 'app'

I don't understand how tox installs the application, and what kind of package structure I need to specify in order to be able to call the code both from the code-base directory and from site packages. I looked at some example projects, and noticed that they don't use the isolated_build flag, but rather the skip_dist flag, but somehow they also install the application in site packages before running their tests.

Any help would be much appreciated.

Specs:

poetry version: 1.1.6
python version:3.6.9 
tox version:3.7
environment: azure windows build agent

Answer 1

You have to change the imports back to from app import something , the src part is, with respect to the code as a deliverable, completely transient. Same goes for adding in another app directory, your initial project structure was fine.

You were right about going from relative imports to absolute ones though, so all that is necessary thereafter is telling your python runtime within the container that root/src should be part of the PYTHONPATH :

export PYTHONPATH="{PYTHONPATH}:/path/to/app/src"

Alternatively, you can also update the path within your python code right before importing your package:

import sys
sys.path.append("/path/to/root/src")

import app  # can be found now

---

Just to state the obvious, meddling with the interpreter in this way is a bit hacky, but as far as I'm aware it should work without any issues.