Ah, fair enough, I misunderstood. I thought the tests they were recommending were tests to ensure backwards-compatibility between version bumps, I didn't realize they were talking about the downstream pacakge's tests.
I still disagree with the insinuation that it's everyone else who's screwing up and if we all did things the way Nix wants us to then Nix would actually work just fine. That's just another way of saying Nix doesn't work in the real world.
It is unfortunate that some in the nix community come off that way, because I would say that in general Nix goes to great lengths to adapt to the world as it is. Especially compared to, say, Bazel.
I myself have been using nix in an org that is blissfully unaware of nix for about 2 years, if that's any indication of how adaptable it can be.
You're totally right. If you're a package maintainer and you find out some package is misbehaving even though all if its included tests pass, it might kinda make you feel like kicking the thing and calling it junk.
But we should recognize that some of what drives that is just defensiveness, and some is personal frustration. At the end of the day, Nix and Nixpkgs are for letting people run useful software more or less as it exists. It's not just for users or developers of perfectly tested, bug-free software. (Nix itself is certainly neither of those things, and neither is Nixpkgs!)
I still disagree with the insinuation that it's everyone else who's screwing up and if we all did things the way Nix wants us to then Nix would actually work just fine. That's just another way of saying Nix doesn't work in the real world.