Improve tracebacks for ImportErrors in conftest #3332
Description
When a conftest file e.g. has an invalid import, we print a verbose traceback with lots of irrelevant pytest internals in it - this seems to confuse people, like in #3112:
Traceback (most recent call last):
File "/home/florian/proj/qutebrowser/git/.tox/py36/lib/python3.6/site-packages/_pytest/config.py", line 329, in _getconftestmodules
return self._path2confmods[path]
KeyError: local('/home/florian/proj/qutebrowser/git/tests')
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/florian/proj/qutebrowser/git/.tox/py36/lib/python3.6/site-packages/_pytest/config.py", line 360, in _importconftest
return self._conftestpath2mod[conftestpath]
KeyError: local('/home/florian/proj/qutebrowser/git/tests/conftest.py')
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/florian/proj/qutebrowser/git/.tox/py36/lib/python3.6/site-packages/_pytest/config.py", line 366, in _importconftest
mod = conftestpath.pyimport()
File "/home/florian/proj/qutebrowser/git/.tox/py36/lib/python3.6/site-packages/py/_path/local.py", line 668, in pyimport
__import__(modname)
File "/home/florian/proj/qutebrowser/git/.tox/py36/lib/python3.6/site-packages/_pytest/assertion/rewrite.py", line 213, in load_module
py.builtin.exec_(co, mod.__dict__)
File "/home/florian/proj/qutebrowser/git/tests/conftest.py", line 24, in <module>
import doesnotexist
ModuleNotFoundError: No module named 'doesnotexist'
ERROR: could not load /home/florian/proj/qutebrowser/git/tests/conftest.py
Compare that with the much nicer input when there's an error inside a test module:
________ ERROR collecting tests/test_conftest.py ________
ImportError while importing test module '/home/florian/proj/qutebrowser/git/tests/test_conftest.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
tests/test_conftest.py:22: in <module>
import doesnotexist
E ModuleNotFoundError: No module named 'doesnotexist'