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Re: How can I hide my stack frames in a TestCase subclass?

From Peter Otten <__peter__@web.de>
Subject Re: How can I hide my stack frames in a TestCase subclass?
Date 2012-10-05 10:12 +0200
Organization None
References <52b17563-966c-46bc-bd77-da29e944c909@googlegroups.com> <mailman.1826.1349400392.27098.python-list@python.org> <k4lum6$c9q$1@thue.elzevir.fr>
Newsgroups comp.lang.python
Message-ID <mailman.1841.1349424768.27098.python-list@python.org> (permalink)

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Manuel Pégourié-Gonnard wrote:

> Peter Otten scripsit :
> 
>> David Banks wrote:
>>
>>> Note that the custom assert method causes a stack trace with two frames,
>>> one inside the method itself, whereas the stock unittest method only has
>>> one frame, the relevant line in the user's code.  How can I apply this
>>> frame-hiding behaviour to my own method?
>>
>> Move MyTestCase in a separate module and define a global variable
>>
>> __unittest = True
>>
> Hum, is it documented somewhere? I can't find it in the doc. Also, I'm
> curious to know what kind of magic it's using.

I took advantage of the fact that Python is open source and had a look into 
the source code ;)

$ cd /usr/lib/python2.7/unittest
$ grep frame *.py -C2
...
result.py-
result.py-    def _is_relevant_tb_level(self, tb):
result.py:        return '__unittest' in tb.tb_frame.f_globals
result.py-
...

$ grep _is_relevant_tb_level *.py -C5
result.py-
result.py-    def _exc_info_to_string(self, err, test):
result.py-        """Converts a sys.exc_info()-style tuple of values into a 
string."""
result.py-        exctype, value, tb = err
result.py-        # Skip test runner traceback levels
result.py:        while tb and self._is_relevant_tb_level(tb):
result.py-            tb = tb.tb_next
result.py-
...

And so on. I actually used an editor, not grep -- but you get the idea.

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Thread

How can I hide my stack frames in a TestCase subclass? David Banks <amoebae@gmail.com> - 2012-10-04 08:53 -0700
  Re: How can I hide my stack frames in a TestCase subclass? Peter Otten <__peter__@web.de> - 2012-10-05 00:41 +0200
    Re: How can I hide my stack frames in a TestCase subclass? Manuel Pégourié-Gonnard <mpg@elzevir.fr> - 2012-10-05 08:28 +0200
      Re: How can I hide my stack frames in a TestCase subclass? Peter Otten <__peter__@web.de> - 2012-10-05 10:12 +0200
        Re: How can I hide my stack frames in a TestCase subclass? Manuel Pégourié-Gonnard <mpg@elzevir.fr> - 2012-10-05 10:50 +0200
          Re: How can I hide my stack frames in a TestCase subclass? Peter Otten <__peter__@web.de> - 2012-10-05 11:26 +0200

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