please don't suppress tracebacks on ImportError during test collection

[cwitty]

This chunk of code in _pytest/python.py (from pytest-3.0.3):

    except ImportError:
        exc_class, exc, _ = sys.exc_info()
        raise self.CollectError(
            "ImportError while importing test module '%s'.\n"
            "Original error message:\n'%s'\n"
            "Make sure your test modules/packages have valid Python names."
            % (self.fspath, exc or exc_class)
        )

ignores the traceback. Please print at least the line and file number of the original failing import.

(I was just refactoring my code, and moved some code around in a way that I knew would cause import errors. But I don't know everywhere this code is imported from, without searching my whole code base or letting my test suite tell me. And if my test suite won't tell me more than "it's broken", then I'm back to searching the code base.)

Minimal example:

(venv) cwitty@helix:/tmp/pttest$ touch a.py
(venv) cwitty@helix:/tmp/pttest$ echo 'from a import anything' > b.py
(venv) cwitty@helix:/tmp/pttest$ echo 'import b' > test_b.py
(venv) cwitty@helix:/tmp/pttest$ pytest

with result:

_________________________ ERROR collecting test_b.py __________________________
ImportError while importing test module '/tmp/pttest/test_b.py'.
Original error message:
'cannot import name 'anything''
Make sure your test modules/packages have valid Python names.

Note that the error message doesn't even mention b.py, the file with the problem.

[nicoddemus]

I agree, I've found the need for this myself on accasion.

[cwitty]

Thank you!