nixos python package (not working)

# default.nix
with import <nixpkgs> {};

let
    pkg = callPackage ./package.nix {
        inherit (pkgs.python37Packages) buildPythonPackage bottle dateutil requests;
    };
in
    pkg

# package.nix
{ buildPythonPackage, bottle, dateutil, requests }:

buildPythonPackage rec {
    pname = "ruterstop";
    version = "0.0.1dev";

    src = ./src;

    # TODO: explicitly require dependencies using fetchPypi with locked versions/hashes
    propagatedBuildInputs = [ bottle dateutil requests ];

    # Run tests manually instead of having to rely on `python setup.py test`
    checkPhase = ''
        python -m unittest tests/*.py
    '';

    meta = {
        description = ''
            Realtime stop info for public transport in Oslo, using the EnTur JourneyPlanner API
        '';
    };
}