A small project to test building an sdist and wheel with tox.

python -m build builds an sdist and then a wheel from it. Here there is a MANIFEST.in that excludes __main__.py. Using

python -m build
pip install dist/testtox-0.1.0-py3-none-any.whl
PYTHONSAFEPATH=1 python -m testtox

gives

.tox/py/bin/python: No module named testtox.__main__; 'testtox' is a package and cannot be directly executed

as does

tox run

while

tox --override testenv.package=wheel run

prints hello, tox because it is packaging __main__.py by skipping the sdist.