Run python -m pip install . before install CI dependencies

[notatallshaw]

I think it would be a good sanity check to use the development version of pip to install the CI dependencies.

This also allows immediately enabling new pip features in the CI, allowing for dogfooding.

[sbidoul]

Sounds reasonable. Should we then use python -m pip to install nox too, to be sure we use the same environment?

[notatallshaw]

Good catch, I'm only using python -m here as upgrading pip via pip install isn't possible on Windows. I hope there aren't two different Python environments here but it's possible.

Also if pip isn't in the same environment as python -m pip it's possible that nox and python -m nox isn't either, so I've replaced all calls to nox as well.

[ichard26]

This seems fine in theory, but I'm not sure if there's a clear benefit? The test environment itself is managed by nox and we already install development pip in those¹. The only change is that nox (and its dependencies) will be installed using development pip.

Footnotes

1. Furthermore, we actually use a PyPI copy of pip to install test suite dependencies to avoid a buggy local pip preventing the test suite from even running at all. ↩