Python – PATH issue with pytest ‘ImportError: No module named YadaYadaYada’

pytestpythonunit testing

I used easy_install to install pytest on a mac and started writing tests for a project with a file structure likes so:

repo/
   |--app.py
   |--settings.py
   |--models.py
   |--tests/
          |--test_app.py

run py.test while in the repo directory, everything behaves as you would expect

but when I try that same thing on either linux or windows (both have pytest 2.2.3 on them) it barks whenever it hits its first import of something from my application path. Say for instance from app import some_def_in_app

Do I need to be editing my PATH to run py.test on these systems? Has Anyone experienced this?

Best Answer

I'm not sure why py.test does not add the current directory in the PYTHONPATH itself, but here's a workaround (to be executed from the root of your repository):

python -m pytest tests/

It works because Python adds the current directory in the PYTHONPATH for you.

Related Solutions

Python – How to import a module given the full path

For Python 3.5+ use:

import importlib.util
spec = importlib.util.spec_from_file_location("module.name", "/path/to/file.py")
foo = importlib.util.module_from_spec(spec)
spec.loader.exec_module(foo)
foo.MyClass()

For Python 3.3 and 3.4 use:

from importlib.machinery import SourceFileLoader

foo = SourceFileLoader("module.name", "/path/to/file.py").load_module()
foo.MyClass()

(Although this has been deprecated in Python 3.4.)

For Python 2 use:

import imp

foo = imp.load_source('module.name', '/path/to/file.py')
foo.MyClass()

There are equivalent convenience functions for compiled Python files and DLLs.

Python – Import a module from a relative path

Assuming that both your directories are real Python packages (do have the __init__.py file inside them), here is a safe solution for inclusion of modules relatively to the location of the script.

I assume that you want to do this, because you need to include a set of modules with your script. I use this in production in several products and works in many special scenarios like: scripts called from another directory or executed with python execute instead of opening a new interpreter.

 import os, sys, inspect
 # realpath() will make your script run, even if you symlink it :)
 cmd_folder = os.path.realpath(os.path.abspath(os.path.split(inspect.getfile( inspect.currentframe() ))[0]))
 if cmd_folder not in sys.path:
     sys.path.insert(0, cmd_folder)

 # Use this if you want to include modules from a subfolder
 cmd_subfolder = os.path.realpath(os.path.abspath(os.path.join(os.path.split(inspect.getfile( inspect.currentframe() ))[0],"subfolder")))
 if cmd_subfolder not in sys.path:
     sys.path.insert(0, cmd_subfolder)

 # Info:
 # cmd_folder = os.path.dirname(os.path.abspath(__file__)) # DO NOT USE __file__ !!!
 # __file__ fails if the script is called in different ways on Windows.
 # __file__ fails if someone does os.chdir() before.
 # sys.argv[0] also fails, because it doesn't not always contains the path.

As a bonus, this approach does let you force Python to use your module instead of the ones installed on the system.

Warning! I don't really know what is happening when current module is inside an egg file. It probably fails too.

Best Answer

Related Solutions

Python – How to import a module given the full path

Python – Import a module from a relative path

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