Document overrides

[woehr]

In particular, jshint is in my package.json and it fails to build because pnpm2nix tries to download the prebuilt phantomjs rather than using the one in nixpkgs. Is there a way to override the jshint dependency so nixpkgs.phantomjs2 is in its environment when it builds?

builder for '/nix/store/x21ik3i8l78n4srb7w8h2fcki64vwjk2-phantomjs-prebuilt-2.1.16.drv' failed with exit code 1; last 10 log lines:
  npm ERR! errno 1
  npm ERR! [email protected] install: `node install.js`
  npm ERR! Exit status 1
  npm ERR! 
  npm ERR! Failed at the [email protected] install script.
  npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
  npm WARN Local package.json exists, but node_modules missing, did you mean to install?
  
  npm ERR! A complete log of this run can be found in:
  npm ERR!     /build/.npm/_logs/2018-11-23T15_41_43_961Z-debug.log
cannot build derivation '/nix/store/mjnxay4f5iv0c1vph7sqkmsan1gn3dd6-jshint-2.9.6.drv': 1 dependencies couldn't be built

[adisbladis]

A dependency can be overriden like this:

let
  pnpm2nix = import /path/to/pnpm2nix;
in pnpm2nix.mkPnpmPackage {
  src = ./.;
  overrides = pnpm2nix.defaultPnpmOverrides // {
      phantomjs2 = (drv: drv.overrideAttrs(oldAttrs: {
        buildInputs = oldAttrs.buildInputs ++ [ pkgs.phantomjs ];
      }));
  };
}

All overrides in https://github.com/adisbladis/pnpm2nix/blob/master/overrides.nix are available through pnpm2nix.defaultPnpmOverrides.

Note: I have not tested this particular override.