Using reverse week deps for Python interpreters and tox (Supplements instead of Recommends)?

[Miro Hrončok]

Hello Pythonistas.

Currently, the tox package has:

# Recommend "all the Pythons"
   Recommends:     python2.7
   Recommends:     python3.6
   Recommends:     python3.7
   Recommends:     python3.8
   Recommends:     python3.9
   Recommends:     python3.10
   Recommends:     pypy2-devel
   Recommends:     pypy3-devel
   Recommends:     python2-devel
   Recommends:     python3-devel

Every time we add or remove a Python interpreter, we need to change the list:

E.g. 
https://src.fedoraproject.org/rpms/python-tox/c/7220117b812d3b5b009b3b1170ee...

What if we added this to all interpreters that work with our tox instead?

Supplements: tox

That way:

- When we introduce a new interpreter,
    tox starts to pull it by default right away.

- When different Fedoras (or even EPELs) have different interpreter sets,
    we don't need to divert the tox spec.

OTOH:

- When we add a new interpreter that Supplements tox, we would still need to 
adapt tox's CI config to include it. Maybe we could adapt the CI tests for tox 
to automatically test with all interpreters that supplement it.

WDYT?

[Petr Viktorin]

On Wed, Aug 11, 2021 at 3:00 PM Miro Hrončok  wrote:
> Hello Pythonistas.
>
> Currently, the tox package has:
>
> # Recommend "all the Pythons"
>    Recommends:     python2.7
>    Recommends:     python3.6
>    Recommends:     python3.7
>    Recommends:     python3.8
>    Recommends:     python3.9
>    Recommends:     python3.10
>    Recommends:     pypy2-devel
>    Recommends:     pypy3-devel
>    Recommends:     python2-devel
>    Recommends:     python3-devel
>
> Every time we add or remove a Python interpreter, we need to change the list:
>
> E.g.
> https://src.fedoraproject.org/rpms/python-tox/c/7220117b812d3b5b009b3b1170ee...
>
> What if we added this to all interpreters that work with our tox instead?
>
> Supplements: tox
>
> That way:
>
> When we introduce a new interpreter,
> tox starts to pull it by default right away.
>
> When different Fedoras (or even EPELs) have different interpreter sets,
> we don't need to divert the tox spec.
>
> OTOH:
> When we add a new interpreter that Supplements tox, we would still need to
>
> adapt tox's CI config to include it. Maybe we could adapt the CI tests for tox
> to automatically test with all interpreters that supplement it.
>
> WDYT?

This looks very reasonable!
Generating the list automatically in tests sounds a bit fragile. For
tests, it might be better to have a manually updated list, and
automatically check if it is up to date.