Umm, there's an issue here. We don't want to proliferate single modules like this one because; all it does is install a zsh plugin and source it in your shell. This is exactly what zsh plugin managers were created for. There is one other, but I'm not fond of this https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/programs/zsh/zsh-autoenv.nix. It would make more sense if you could use just nix for this even. Home-manager has a functionality for this https://github.com/rycee/home-manager/blob/master/modules/programs/zsh.nix#L258, but I believe it makes much more sense there. This is because it can be scoped per user, and not the global shell. But I'm not opposed to that in nixos.

And about the test, it does make verifying the function easy.
At most, I could merge it. But it also makes me think zsh-history could provide integration testing to obsolete a nixos test, and better.

A pure way could maybe be done with https://github.com/google/goexpect, but I don't code go.
I just know Nix has a restriction with interactive shell during the build, so to work in the most compatible way would be something like expect. And a buildtime testsuite could be nice too, but it's just a zsh plugin.

Alright, since this is fairly trivial, I have no issues with maintaining it off-branch.
Thanks for reviewing anyways 👍

@kampka The test was fine though. Lmk if you want that merged.