Test perl bindings with nix-serve

[roberth]

Motivation

Avoid being caught by surprise when updating nix in Nixpkgs.

Alternatives:

• Deprecate the perl bindings in favor of new bindings built on the C API.
  • Not stable yet
  • Virtually no store-layer interface yet in the C API
• Write a test suite for the perl bindings, so that these tests are local again, possibly with better coverage. I doubt that the effort is worth it.

Context

• See context of Support Nix::Store from 2.21 onwards edolstra/nix-serve#60

• Blocked on experimental feature flag as in nix-serve: unstable-2018-03-20 → unstable-2024-09-17 nixpkgs#342714

  • or modules.nixosTest.setPackage: init nixpkgs#299542

Priorities and Process

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[Ericson2314]

There is a tiny test suite for the perl bindings, but it is indeed not useful for seeing if certain apps have upgraded. In this case the breaking change in the Perl bindings was intentional, so a mere test suite would not have caught it.

[Ericson2314]

I think I would rather not do that here (it doesn't work with the split packages so well), and instead just slap on the attribute for the nix-serve override.

[Ericson2314]

+1 on the concept

[edolstra]

I'm 👎 on this, since nix-serve is a (not very well maintained) downstream on Nix. It shouldn't be tested here but in the nix-serve project. We already have enough "noise" in terms of failing nix:master Hydra jobs, so I don't want to add another job that is perpetually failing. We also don't have an easy way to fix nix-serve here, i.e.

          nix-serve =
            prev.nix-serve.override {
              # undo potential version pinning
              nix = final.nix;
            };

takes the nix-serve from Nixpkgs rather than nix-serve master.

[roberth]

We also don't have an easy way to fix nix-serve here

In other projects, I've added overrides conditioned on e.g. inputs?nix-serve, so that could make it easy to switch to a different version.

We already have enough "noise" in terms of failing nix:master Hydra jobs

👍 let's make sure to fix that.

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/2024-09-18-nix-team-meeting-minutes-179/52361/1

[Mic92]

I worked on improving testing in nix-serve here: edolstra/nix-serve#61

[Mic92]

Downstream maintainer of nix-serve is against this idea.