{ config, lib, pkgs, ... }: { config = { programs.mpv = { enable = true; package = pkgs.mpvDummy; scripts = [ pkgs.mpvScript ]; }; nixpkgs.overlays = [ (self: super: { mpvScript = pkgs.runCommandLocal "mpvScript" { scriptName = "something"; } "mkdir $out"; }) ]; test.stubs.mpvDummy = { }; test.asserts.assertions.expected = [ '' The programs.mpv "package" option is mutually exclusive with "scripts" option.'' ]; }; }