Python preference

[RomainBrault]

This PR enables the usage of the flag --python-preference to better control which Python interpreter is used.

See https://docs.astral.sh/uv/python-versions/#adjusting-python-version-preferences

It does so by exposing a uv_python_preference configuration field.

Note: this can be used to download missing Python interpreter. Use for example

[testenv]
uv_python_preference = only-managed

[gaborbernat]

tox-uv does not interact with uv python, only with uv venv. Doesn't the later only uses system pythons?

[gaborbernat]

tox-uv does not interact with uv python, only with uv venv. Doesn't the later only uses system pythons?

[RomainBrault]

tox-uv does not interact with uv python, only with uv venv. Doesn't the later only uses system pythons?

using python_preference = managed allows uv venv to use uv python toolchain if my understanding is correct.

I proposed this PR as it allows me to stop worrying about my python versions installed on my system and let tox-uv manage this through uv python.

By default no flag is passed to uv venv preserving the old behaviour. If python_preference is set, the flag --python-preference is passed, controlling wjether to use system python or some uv managed python.

[gaborbernat]

using python_preference = managed allows uv venv to use uv python toolchain if my understanding is correct.

Can you link to upstream docs of this?

[RomainBrault]

using python_preference = managed allows uv venv to use uv python toolchain if my understanding is correct.

Can you link to upstream docs of this?

https://docs.astral.sh/uv/python-versions/#adjusting-python-version-preferences

Should be in the README.md too.

[gaborbernat]

The CI is broken.

[RomainBrault]

Blocking now with the typing error. Optional or Union[Type, None] are not working. Investigating.

[RomainBrault]

At this point the CI pass locally

[gaborbernat]

Seem it is not. Note you can setup https://github.com/RomainBrault/tox-uv/actions to not need to wait for my approval.

[RomainBrault]

Here we go. I had to remove some type information to make it compatible with Python <3.10.

Thank you for your patience.

[gaborbernat]

[gaborbernat]

[bluss]

I guess this is why I reported #72

I thought tox-uv didn't "do this" because it was not advertised, and some open issues suggested otherwise. This is a feature that has just turned up, because uv venv already does it depending on configuration (that I already had).

Oh and it's a preview feature in uv so in that sense I guess it makes sense to not make any guarantees about it.