How To Add A Package To Sys Path For Testing

This question is occasioned by instructions in the python guide for adding a project to sys path to use in tests, which do not seem to work unless I am misunderstanding the instruc

Solution 1:

Question: How can I add my sample package to the sys path correctly?

You're doing it the right way, but you missed declaring your folder to be a package. Try solution of Christian, it should work.

Your path is stored in sys.path. By doing this:

sys.path.insert(0, os.path.abspath('..'))

You're telling your python to add upper folder (of current file) into your path. As sys.path is a list, you can using other methods of list like insert, append...

In your case, you're inserting your upper dir at top of the path list.

See:

In [1]: import sys

In [2]: sys.path
Out[2]: 
['',
 '/usr/local/bin',
 '/usr/lib/python3.4',
 '/usr/lib/python3.4/plat-x86_64-linux-gnu',
 '/usr/lib/python3.4/lib-dynload',
 '/usr/local/lib/python3.4/dist-packages',
 '/usr/lib/python3/dist-packages',
 '/usr/local/lib/python3.4/dist-packages/IPython/extensions',
 '/home/cuong/.ipython']

In [3]: sys.path.insert(0, '/tmp/foo')

In [4]: sys.path
Out[4]: 
['/tmp/foo', **<-- on top**'',
 '/usr/local/bin',
 '/usr/lib/python3.4',
 '/usr/lib/python3.4/plat-x86_64-linux-gnu',
 '/usr/lib/python3.4/lib-dynload',
 '/usr/local/lib/python3.4/dist-packages',
 '/usr/lib/python3/dist-packages',
 '/usr/local/lib/python3.4/dist-packages/IPython/extensions',
 '/home/cuong/.ipython']

So, from here, when you have

import sample

your python will try to look in path to see if there is any sample package.

Unfortunately, it can't find sample as you didn't make it as a package because your forgot __init__.py in sample folder.

Hope my explanation would help you to understand and you can handle other situations different to this.

Solution 2:

Try adding an empty __init__.py to tests/: touch tests/__init__.py should do it.

Solution 3:

I had a battle to get my testing directory structure to work outside of an IDE. Please find my solution below. Tested on Windows 7 using python 3.6 and Linux Mint using python 3.4, running the code using the command line:

python -m pytest test_compress_files.py

The file I wrote to be tested is called compress_files.py in a directory named \src. The file containing tests to be run using pytest is called test_compress_files.py in a subdirectory \tests, so the full directory path is \src\tests. I needed to add a file called context.py to the \src\tests directory. This file is used in test_compress_files.py to enable access to compress_files.py in the directory above. The _init_.py files are empty.

Directory structure

\src
__init__.py
compress_files.py

\src\tests
__init__.py
context.py
test_compress_files.py

compress_files.py contains the script to be tested.

context.py:

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

import compress_files  

The line:

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

comes from the suggestion at the hitch hikers guide to python at http://docs.python-guide.org/en/latest/writing/structure/. This adds the path of the directory above the /src/tests directory to sys.path, which in this case is /src.

test_compress_files.py:

import os
import pytest
from .context import compress_files
from compress_files import *

# tests start here
...

Solution 4:

I can't comment yet but i was trying out Oppy's answers in python 3.7 env and it fail as:

ImportError: cannot import name 'compress_files' from '__main__' (test_compress_files.py)

I resolved using a modified test_compress_files.py (notice the removed dot) :

import os
import pytest
from context import compress_files
from compress_files import *

# tests start here
...