Hey Smell This: In the spirit of my Shell Grymoire, here are some useful Nix invocations/patterns/commands.

Adding a flake check to run pytest

checks.pytest = pkgs.stdenvNoCC.mkDerivation {
  name = "pytest";
  src =./.;
  dontBuild = true;
  doCheck = true;
  nativeBuildInputs = [
    pkgs.python3.pkgs.pytest
    pkgs.callPackage ./default.nix {};
  ];
  checkPhase = "pytest test";
  installPhase = "mkdir $out";
};

Disable remote builds in a derivation

Add NIX_CONFIG = "builders ="; to the derivation (and thus process environment)

Calculate a Nix hash from Nix Version Pins

(or you can just invoke the Magic contained in the Version Pins document)

nix-build --expr '(import <nixpkgs> {}).fetchFromGitHub (import /home/rrix/arroyo-nix/versions.nix {}).org-fc' | xargs -n1 nix hash path