10

I thought py.test is "standalone" in a sense that it treats test_*.py files "as it is", and only imports modules specified in these files, with no respect to any surrounding files. It looks like I'm wrong. Here is my dialog with py.test:

$ ls
__init__.py    test_pytest.py
$ cat __init__.py 
$ cat test_pytest.py 
def test_pytest():
    assert True
$ py.test test_pytest.py 
========================================================= test session starts ==========================================================
platform darwin -- Python 2.7.2 -- pytest-2.1.3
collected 0 items / 1 errors 

================================================================ ERRORS ================================================================
___________________________________________________ ERROR collecting test_pytest.py ____________________________________________________
/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/py-1.4.5-py2.7.egg/py/_path/local.py:529: in pyimport
>           mod = __import__(modname, None, None, ['__doc__'])
E           ImportError: No module named test_pytest
======================================================= 1 error in 0.01 seconds ========================================================
$ rm __init__.py 
$ py.test test_pytest.py 
========================================================= test session starts ==========================================================
platform darwin -- Python 2.7.2 -- pytest-2.1.3
collected 1 items 

test_pytest.py .

======================================================= 1 passed in 0.01 seconds =======================================================
$

How do I make py.test work and still have my __init__.py files?

UPDATE

In comments, Holger Krekel asked, what is the name of parent directory. And it turns out that I can reproduce the error above only having a certain parent directory name (e.g. the same name as one of the packages installed, like distutils). See here: 

~/test_min 
$ tree
.
└── distutils
    ├── __init__.py
    └── test_pytest.py

1 directory, 2 files
~/test_min 
$ cat distutils/__init__.py 
~/test_min 
$ cat distutils/test_pytest.py 
def test_pytest():
    assert True
~/test_min 
$ py.test distutils/test_pytest.py 
======================== test session starts =========================
platform darwin -- Python 2.7.2 -- pytest-2.1.3
collected 0 items / 1 errors 

=============================== ERRORS ===============================
_____________ ERROR collecting distutils/test_pytest.py ______________
/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/py-1.4.5-py2.7.egg/py/_path/local.py:529: in pyimport
>           mod = __import__(modname, None, None, ['__doc__'])
E           ImportError: No module named test_pytest
====================== 1 error in 0.01 seconds =======================
~/test_min 
$ rm distutils/__init__.py 
~/test_min 
$ py.test distutils/test_pytest.py 
======================== test session starts =========================
platform darwin -- Python 2.7.2 -- pytest-2.1.3
collected 1 items 

distutils/test_pytest.py .

====================== 1 passed in 0.01 seconds ======================
~/test_min 
$ touch __init__.py
~/test_min 
$ ls
__init__.py distutils
~/test_min 
$ touch distutils/__init__.py
~/test_min 
$ py.test distutils/test_pytest.py 
======================== test session starts =========================
platform darwin -- Python 2.7.2 -- pytest-2.1.3
collected 1 items 

distutils/test_pytest.py .

====================== 1 passed in 0.02 seconds ======================
~/test_min 
$ rm __init__.py 
~/test_min 
$ py.test distutils/test_pytest.py 
======================== test session starts =========================
platform darwin -- Python 2.7.2 -- pytest-2.1.3
collected 0 items / 1 errors 

=============================== ERRORS ===============================
_____________ ERROR collecting distutils/test_pytest.py ______________
/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/py-1.4.5-py2.7.egg/py/_path/local.py:529: in pyimport
>           mod = __import__(modname, None, None, ['__doc__'])
E           ImportError: No module named test_pytest
====================== 1 error in 0.01 seconds =======================
~/test_min 
$ mv distutils foobar
~/test_min 
$ py.test foobar/test_pytest.py 
======================== test session starts =========================
platform darwin -- Python 2.7.2 -- pytest-2.1.3
collected 1 items 

foobar/test_pytest.py .

====================== 1 passed in 0.01 seconds ======================
~/test_min 
$

Hope this additional information will help.

Vladimir Keleshev
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    Sounds like you're probably running into a side-effect of Python's package system. – Chris Morgan Nov 23 '11 at 15:15
  • What happens if you include the __init__.py file and only say ... $ py.test – jcfollower Nov 23 '11 at 16:19
  • It looks like there might be a hint to your issue at the bottom of ... http://pytest.org/latest/goodpractises.html#package-name – jcfollower Nov 23 '11 at 16:20
  • For what is worth, I haven't seen that behaviour in version 1.3.4. However, I've updated to version 2.2.0 to give it a try and got the same error output. – jcollado Nov 23 '11 at 17:10
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    what is the name of the parent directory (the one containing the __init__.py)? Are there further __init__.py files involved further up in the directories which contain code? – hpk42 Nov 24 '11 at 10:33

3 Answers3

17

Looks like py.test is using py._path.pyimport to open your file. If there is a __init__.py file in the directory, it treats your file as a module, otherwise it opens the file. Long story short, delete the __init__.py or put your tests in another directory outside your project code (<--- good idea).

https://py.readthedocs.io/en/latest/path.html#py._path.local.LocalPath.pyimport

SuperStormer
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Bashwork
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    I awarded you the bounty so that it will not automatically be given to tito, since his answer is incorrect. Though, I hoped to solve this problem without changing file structure. – Vladimir Keleshev Dec 12 '11 at 12:04
7

I really suggest you to rename the directory to something not called "distutils". Why ? Because you are overriding an existing module. When "import distutils" or "from distutils import *" appear in the script (from another import or your own python file), it will prefer your directory instead the system one. If the module distutils have been already loaded before, your distutils will not be loaded, because the symbol already exists in global().

It would be really simpler to rename that directory (like tests) instead of trying to fight with py.test / python internals.

Alexander Klimenko
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tito
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  • distutils is just an example to reproduce an error. I have problems with my own module with different name. – Vladimir Keleshev Dec 06 '11 at 15:58
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    Ok, one last question. When you add __init__.py on '.', the name of the '.' directory is taken as a module name too. What is it in your case ? (a side note also, even if by looking at your tests, i don't think you're hit this bug, but don't forget about the pyc generation, when removing py, pyc is still exist and importable.) – tito Dec 06 '11 at 23:06
  • if you mean, when I do `$ touch __init__.py`? It is done in `~/test_min` as you can see from the line above. Also, I don't have any pyc files, as you can see from the [`tree`](http://mama.indstate.edu/users/ice/tree/) command. – Vladimir Keleshev Dec 07 '11 at 08:04
4

You can tell pytest to ignore specific files or glob patterns as described here. Put a conftest.py file in the root directory of your project that lists the files you want pytest to ignore:

However, many projects will have a setup.py which they don’t want to be imported. Moreover, there may files only importable by a specific python version. For such cases you can dynamically define files to be ignored by listing them in a conftest.py file:

 # content of conftest.py
 import sys

 collect_ignore = ["setup.py"]
Will
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