nixosTests.networkingProxy: port to Python

[andrew-d]

Motivation for this change

#72828

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @tfc @ardumont

[andrew-d]

@tfc - Yep, can do for both. As a general question: for these sorts of "porting tests" PRs, would it be better to do a mechanical line-by-line translation (like I did here), or a more general rewrite?

[tfc]

@tfc - Yep, can do for both. As a general question: for these sorts of "porting tests" PRs, would it be better to do a mechanical line-by-line translation (like I did here),

this is what i did when the whole project began, as i don't understand how all of the tested services really work. Then a 1:1 port was the minimal feasible thing to do.

or a more general rewrite?

If you are the maintainer of the service, the test, or simply happen to know how the tested service really works and ought to be tested, a rewrite that makes it better/more readable/more structured is always welcome!

[andrew-d]

@flokli @tfc - Okay, since improvements are okay, I rewrote the tests to use more modern Python, remove duplication, and use proper assertions.

[andrew-d]

@flokli @tfc - ping! Anything I can do to keep this moving forward?

[tfc]

@andrew-d sorry didn't see the latest changes. I think @flokli is pretty busy at the time.

cc @worldofpeace

[tfc]

@GrahamcOfBorg test networkingProxy

[worldofpeace]

Fixed commit message.