nixos/testing: Add test attribute to please discoverTests

[roberth]

• discoverTests is bankrupt in tech debt, so we work around it until Tracking: migrate NixOS handleTest -> runTest #386873 is done.

• This is in response to NixOS test framework: add overriding methods #421480 (comment)

This makes it a happy lambda again:

$ nix eval --impure --expr 'with import ./. {}; bind.tests.kubernetes-dns-multi-node.extend'
«lambda extend @ /home/user/src/nixpkgs-master/nixos/lib/testing/call-test.nix:31:7»

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• Nixpkgs 25.11 Release Notes (or backporting 25.05 Nixpkgs Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
• NixOS 25.11 Release Notes (or backporting 25.05 NixOS Release notes)
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other contributing documentation in corresponding paths.

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Add a 👍 reaction to pull requests you find important.

[MattSturgeon]

Diff looks good. I've not tested if this resolved the reported issue.

[wolfgangwalther]

Diff LGTM; but I can't tell whether it's enough, or whether there are any other cases that will still throw similarly.

[wolfgangwalther]

@trofi can you run your script on this branch again and see whether there are any other regressions from that PR?

[trofi]

@trofi can you run your script on this branch again and see whether there are any other regressions from that PR?

No regressions.

[wolfgangwalther]

@trofi I saw your approval was gray not green, indicating you're not a committer. My journey ultimately lead me to NixOS/nixpkgs-committers#60 (comment) - and I wanted to ask whether your situation has maybe changed today? Your activity on GitHub and Nixpkgs seems to indiciate - to me - that maybe, hopefully, that could be the case.

[trofi]

No, no improvement. It's actually the other way around: I had to cut down a few more nixpkgs activities I used to have more time for.