Disable Python package check in Nix

When deploying Python service to staging using Nix, I want to disable checks for that Python package. (Checks already happened in CI anyway.)

Obvious question is how; obvious answer is overrides. Then, let me reformulate that obvious question a bit: which one?

Giving up on the documentation, the nixpkgs source is a bit helpful:

Derivations built with buildPythonPackage can already be overridden with override, overrideAttrs, and overrideDerivation.

This function introduces overridePythonAttrs and it overrides the call to buildPythonPackage.

This is the relevant overlay:

overlays = {
  do-not-check-pypkg = final: prev: let
    pypkg-wo-check = f: p: {
      pypkg = p.pypkg.overridePythonAttrs { doCheck = false; };
    };
  in
  {
    pythonPackagesExtensions =
      prev.pythonPackagesExtensions
      ++ [ats-wo-check];
  };
};

and then nixpkgs.overlays = [self.overlays.do-not-check-pypkg];.

• do-not-check-pypkg is an overlay for Nixpkgs, which extends the pythonPackagesExtensions attribute – a list of overlays (for Python packages) that are applied to the Python packages at once.

• pythonPackagesExtensions is extended by pypkg-wo-check overlay.

• pypkg-wo-check is an overlay for Python packages, which disables check for the pypkg Python package.