Nix Shell for local development on Python projects. Ideal for mixed teams that doesn't have full Nix buy-in

shell.nix

{ pkgs ? import <nixpkgs> {} }:
  pkgs.mkShell {
    nativeBuildInputs = with pkgs; [
      python3
    ];

    shellHook = ''
      if [ -d ".venv" ]
      then
          echo "Using existing virtual env"
      else
          echo "Setting up virtual env"
          python3 -m venv .venv
          pip3 install --user -r ./requirements-test.txt
      fi && source .venv/bin/activate
    '';
  }