Wrong "Recursion detected" in py.test traceback

[pytestbot]

Originally reported by: BitBucket: pchambon, GitHub: pchambon

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Hello,

I've just spent a hell of a time trying to debug a "Recursion detected (same locals & position)" that my test suite raised, to eventually see that it was not a python error, but a pytest problem while collecting test results.

Due to the "magic" used in the program (decorator module), pytest thought there was a recursion, whereas several functions were simply using generated wrappers to preserve their signature while decorating.

The main problem is actually that the real exception (a runtime error, in the test sample) got hidden because of that "recursion detected" (see output below), thus deceiving me about the real problem. Having a fix to ignore "" entries, when detecting traceback recursions, would be neat too.

CF attached sample to reproduce the error ("decorator" module must tbe installed).

cheers,
P. Chambon

#!python

[pascal@charlie ~/test]$ py.test weird_recursion.py
====================================== test session starts =======================================
platform freebsd8 -- Python 2.6.6 -- pytest-2.0.3
collected 0 items / 1 errors

============================================= ERRORS =============================================
______________________________ ERROR collecting weird_recursion.py _______________________________
weird_recursion.py:32: in <module>
>   test_tolkien_weird_recursivity()
weird_recursion.py:29: in test_tolkien_weird_recursivity
>           retrieve_stuffs("0654345654123")
<string>:2: in retrieve_stuffs
>   ???
weird_recursion.py:11: in mymiddleware
>           res = func(*args, **kwargs)
<string>:2: in retrieve_stuffs
>   ???
!!! Recursion detected (same locals & position)
---------------------------------------- Captured stderr -----------------------------------------
NOW WE RAISE ERROR
==================================== 1 error in 0.15 seconds =====================================

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• Bitbucket: https://bitbucket.org/pytest-dev/pytest/issue/70

[pytestbot]

Original comment by Ronny Pfannschmidt (BitBucket: RonnyPfannschmidt, GitHub: RonnyPfannschmidt):

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it seems that FunctionMaker of the decorator package generates code + code objects with properties that end up looking exactly like recursion even if they are not

im not sure how to work around that, and if we even should try to work around that

[pytestbot]

Original comment by BitBucket: pchambon, GitHub: pchambon:

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Indeed, but there would be something to do in terms of clarity:

• replacing "recursion detected" by a more relevant detail, eg. "Potential recursion detected by pytest - truncating traceback" ?
• letting at the bottom, in red color, the actual exception that caused the traceback (it gets swallowed by the traceback truncation, in my example)

Then people would not believe (as I did) that the recursion has been detected by the python runtime.

[pytestbot]

Original comment by holger krekel (BitBucket: hpk42, GitHub: hpk42):

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We could at least adapt the error message, indeed. Is there really no way to recognizethese decorators?

[pytestbot]

Original comment by Ronny Pfannschmidt (BitBucket: RonnyPfannschmidt, GitHub: RonnyPfannschmidt):

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fixed in pylib default now

[pytestbot]

Original comment by Anonymous:

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1000 thanks B-)