sage --pytest does not support out of Sage tree Sage doctests

[dimpase]

Running sage --pytest foo.py on an out of tree foo.py ignores sage:-prompted docstrings, and happily tests >>>-prompted docstrings. E.g. with

# foo.py
class tst:
    """
    sage: len(tst.__subclasses__()) >= 0
    True
    """
    pass

one has

$ ./sage --pytest src/sage/interfaces/foo.py 
===================================== test session starts ======================================
platform linux -- Python 3.9.2, pytest-7.1.3, pluggy-1.0.0
rootdir: /home/dimpase/work/software/sage/src, configfile: tox.ini
collected 1 item                                                                               

src/sage/interfaces/foo.py .                                                               [100%]

====================================== 1 passed in 0.04s =======================================

but

$ ./sage --pytest foo.py 
===================================== test session starts ======================================
platform linux -- Python 3.9.2, pytest-7.1.3, pluggy-1.0.0
rootdir: /home/dimpase/work/software/sage/src
collected 0 items                                                                              

==================================== no tests ran in 0.01s =====================================

So there is some magic happening here, with tox.ini used in the former case, but not in the latter case.

Component: doctest framework

Issue created by migration from https://trac.sagemath.org/ticket/34829

[mkoeppe]

comment:1

src/conftest.py has the magic

[mkoeppe]

comment:2

It would probably be sufficient if we document how user projects should configure pytest by providing their own confest.py

[dimpase]

comment:3

Replying to Matthias Köppe:

src/conftest.py has the magic

Thanks. Perhaps you also know where to monkey-patch warnings.showwarning - see
#33826 comment:8 -
so that pytest correctly processes deprecation warnings in doctests...

[dimpase]

comment:4

Oh, it can be monkey-patched in src/conftest.py - it's in a diffrent format then, so that's something to look into...