Error importing module is not properly treated in pytest (fails with UnicodeEncodeError from pytest) #2336
Description
pytest version: 3.0.5, OS: Windows 10, python: 2.7.12
We have an intermittent issue when running pytest in that a module won't be properly loaded when imported by pytest. I still don't know the real reason for the issue (could be pytest related or not, still unsure as it's flaky on our ci)... anyways, the known problem on pytest is that pytest hides the real error by giving an UnicodeEncodeError instead of printing the original message (the error is below).
It seems that the problem is that it's mixing bytes and unicode on python 2:
formatted_tb = py._builtin._totext(exc_repr) # unicode on python 2, and the .format() call is made on a bytes array.
Exception given by pytest:
W:\py27-win64\lib\site-packages\_pytest\runner.py:163: in __init__
self.result = func()
W:\py27-win64\lib\site-packages\_pytest\main.py:464: in _memocollect
return self._memoizedcall('_collected', lambda: list(self.collect()))
W:\py27-win64\lib\site-packages\_pytest\main.py:335: in _memoizedcall
res = function()
W:\py27-win64\lib\site-packages\_pytest\main.py:464: in <lambda>
return self._memoizedcall('_collected', lambda: list(self.collect()))
W:\py27-win64\lib\site-packages\_pytest\python.py:411: in collect
self.session._fixturemanager.parsefactories(self)
W:\py27-win64\lib\site-packages\_pytest\fixtures.py:1064: in parsefactories
holderobj = node_or_obj.obj
W:\py27-win64\lib\site-packages\_pytest\python.py:215: in fget
self._obj = obj = self._getobj()
W:\py27-win64\lib\site-packages\_pytest\python.py:408: in _getobj
return self._memoizedcall('_obj', self._importtestmodule)
W:\py27-win64\lib\site-packages\_pytest\main.py:335: in _memoizedcall
res = function()
W:\py27-win64\lib\site-packages\_pytest\python.py:445: in _importtestmodule
"{traceback}".format(fspath=self.fspath, traceback=formatted_tb)
E UnicodeEncodeError: 'ascii' codec can't encode character u'\ufffd' in position 110: ordinal not in range(128)