[all][tc] Dropping lower-constraints testing from all projects

Radosław Piliszek radoslaw.piliszek at gmail.com
Thu Jan 7 16:55:44 UTC 2021

On Thu, Jan 7, 2021 at 5:42 PM Jeremy Stanley <fungi at yuggoth.org> wrote:
> On 2021-01-07 10:15:59 +0000 (+0000), Stephen Finucane wrote:
> [...]
> > Out of curiosity, would limiting the list in lower-constraints to
> > the set of requirements listed in 'requirements.txt' help matters?
> > That would at least ensure the lower version of our explicit
> > dependencies worked. The main issue I could see with this is
> > potentially a lot of thrashing from pip as it attempts to find
> > versions of implicit dependencies that satisfy the various
> > constraints, but I guess we'll have to address that when we come
> > to it.
> You can try it locally easily enough, but my recollections from
> before is that what you'll find for larger projects is old releases
> of some dependencies don't pin upper bounds of their own
> dependencies and wind up not being usable because they drag in
> something newer than they can actually use <snip>

This is also why we can't really have a smart-enough solver trying to
minimize dep versions as some have no bounds on either side. What
would the verdict then be? If it was to install the oldest version
ever, I bet it would fail most of the time.

For me, lower constraints are well too complicated to really get
right, and, moreover, checking only unit tests with them is likely not
useful enough to warrant that they result in working deployments.

I don't envy distro packagers but really the only thing they can bet
on is deciding on a set of packaged deps and running tempest against
the curated deployment (plus unit tests as they are much cheaper
Thanks to upper-constraints we know there is at least one combination
of deps that will work. We can't really ensure any other in a simple


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