[pganssle]

This is at worst a lateral move — you need something installed that handles your test invocation for you. It could be `make`, `tox`, `nox`, `poetry` or whatever.

For a number of reasons (detailed in the article), that thing shouldn't be `setuptools`. Even if the setuptools maintainers wanted to continue supporting this use case, setuptools is uniquely unsuited to working with this, because of the way its hooks don't fire until all its dependencies have been imported already. With `tox` you just need to make sure you have `tox` installed, and you can even specify a minimum version in the `tox.ini` file.

Additionally, tox doesn't need to be installed in your Python environment (in fact, it's an implementation detail that it's Python at all — if it were instead a Go executable, it would work the same). You just need the tool available to be invoked. This means you can install it with pipx, in its own virtual environment, through your system package manager, whatever is most convenient for you.