Hatch Test System Python Option

[blink1073]

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We're looking into adopting the hatch test pattern in jupyter_server, but are stuck on the fact that pypy isn't supported. What we'd like to be able to do is tell hatch test to use the system python $(which python) in our CI.

[ofek]

Hey! Do you mean you have an environment already set up with the proper dependencies and you want to avoid that step and start running scripts without any setup phase?

[blink1073]

I mean effectively UV_SYSTEM_PYTHON since we're using uv under the hood.

[SupImDos]

I ran into a similar issue in my CI, which I fixed by setting the HATCH_PYTHON environment variable to the appropriate path: https://github.com/SupImDos/pydantic-argparse/pull/67

It seems like there should be a better / more intuitive way to do this though. Without having thought about it too much, I'm not sure that the preferred Python should be the one Hatch is using - especially since Hatch seems to install Python 3.12 along with itself (at least in CI).

https://github.com/pypa/hatch/blob/d73037fe7e9b66eeeba2e72d37074373594221c5/src/hatch/env/virtual.py#L325-L333

Maybe the resolution order should prefer the Python version in the active shell (i.e., $(which python)) first?