Remove tests from distributions, or put in-tree, or... ?

[bollwyvl]

site-packages/tests is a total dumping ground, and basically useless for anybody.

However, including the tests in the distribution can be useful, but in-tree, such that they can be run with pytest --pyargs nbclassic, as well as potentially making test things useful to downstreams, e.g. from nbclassic.tests import useful_fixture. Or whatever.

So, I propose one of:

• ignore tests with find_packages(".", exclude=["tests"])
• keep tests where they are, but move nbclassic into src, and do find_packages there
• move tests into nbclassic

In the interim, I'm working up a PR to the conda-forge feedstock, where a janky site-packages/tests cause particular issues for downstream conda tools, e.g. constructor, which really (and rightly!) don't like two packages trying to write to the same file... in this case, tests/conftest.py.