nixosTests.kernel-generic: avoid kernel aliases

[philiptaron]

I discovered these searching for things under nixosTests that didn't evaluate.

It doesn't seem worth it to claim to have a test for kernels that aren't actually in nixpkgs.

Also, remove a top-level with statement and reshape the code to continue working.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
• Fits CONTRIBUTING.md.

[Atemu]

The diff LGTM but I'm not so sure about the intent.

I get where you're coming from but I think it'd be confusing behaviour to just have the attribute disappear if the kernel doesn't eval for whatever reason. It's much preferable to eval a test for a certain kernel and then have it blow up in your face stating that it can't eval because the kernel has some issue.

If you only wanted to eval tests that don't throw, you should just filter that at the NixOS test level.

I think what this mostly comes down to is the question: What's so bad about NixOS tests that (rightfully) don't eval?

What I'd be fine with as an alternative would be a sort of opt-in test eval mode where tests that don't eval are removed.