ImportError显示py.test，但在运行应用程序时不显示

Question

Unlike in this question: Importing modules from a sibling directory for use with py.test I can import something from my app, but there's an import error (looking like a circular dependency) that raises from 'inside' myapp while running the test and not when running myapp alone:

$ python3 myapp/myapp.py
Some dummy string (correct output)

But:

$ python3 -m pytest                                                                               
================================================================= test session starts =================================================================
platform linux -- Python 3.4.3, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
rootdir: /home/nico/temp/projects_structures/test04/myapp, inifile: 
plugins: cov-2.2.1
collected 0 items / 1 errors 

======================================================================= ERRORS ========================================================================
________________________________________________________ ERROR collecting tests/test_things.py ________________________________________________________
tests/test_things.py:4: in <module>
    from myapp.lib.core.base import do_things
myapp/lib/core/base.py:1: in <module>
    from lib import something
E   ImportError: No module named 'lib'
=============================================================== 1 error in 0.05 seconds ===============================================================

As you can see, the problem is not the import statement from the test file. It's raised from 'inside' myapp .

Here is the complete structure:

.
└── myapp
    ├── myapp
    │   ├── __init__.py
    │   ├── lib
    │   │   ├── core
    │   │   │   ├── base.py
    │   │   │   └── __init__.py
    │   │   └── __init__.py
    │   └── myapp.py
    └── tests
        └── test_things.py

myapp.py contains:

#!/usr/bin/env python3

from lib.core import base

base.do_things()

lib/__init__.py contains:

something = "Some dummy string (correct output)"

base.py contains:

from lib import something

def do_things():
    print(something)
    return True

and test_things contains:

import unittest
import sys
sys.path.insert(0, '..')
from myapp.lib.core.base import do_things

class DoThingsTestCase(unittest.TestCase):

    def test_do_things(self):
        self.assertTrue(do_things())

if __name__ == '__main__':
    unittest.main()

And $PYTHONPATH seems correctly set (so this: Py.test No module named * doesn't answer my problem). (Or if this is not correct, how can I correct it?)

$ echo $PYTHONPATH
/home/nico/temp/projects_structures/test04/myapp/myapp

Answer 1

Setting the PYTHONPATH should do the trick.

$ export PYTHONPATH=<ABSOLUTE PATH TO TOPMOST myapp dir>

(in this example, it is the path to myapp/myapp; and ensure you've exported PYTHONPATH , not only set it).

and from myapp run either

$ py.test

or

$ python3 -m pytest

Answer 2

Another way of doing this is to put a conftest.py file into the top level of myapp , or in myapp/tests . Like this:

$ pwd
/home/nico/temp/projects_structures/test04/myapp/tests
$ touch conftest.py
$ cd ..
$ py.test
================================================================= test session starts =================================================================
platform linux2 -- Python 2.7.6, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
rootdir: /home/nico/temp/projects_structures/test04/myapp, inifile: 
collected 1 items 

tests/test_things.py .

============================================================== 1 passed in 0.05 seconds ===============================================================
$

(and PYTHONPATH is empty:

$ echo $PYTHONPATH

$

)

This way, py.test automatically adds myapp to PYTHONPATH . This avoids to forget exporting PYTHONPATH and will make the tests of myapp easier for other devs (who neither will need to solve this problem).