{ pkgs, ... }: {
  config = {
    programs.bash.enable = true;
    programs.fish.enable = true;
    programs.zsh.enable = true;

    programs.command-not-found.enable = true;

    nixpkgs.overlays =
      [ (self: super: { zsh = pkgs.writeScriptBin "dummy-zsh" ""; }) ];

    programs.nix-index.enable = true;

    # 'command-not-found' does not have a 'fish' integration
    test.asserts.assertions.expected = [
      ''
        The 'programs.command-not-found.enable' option is mutually exclusive
        with the 'programs.nix-index.enableBashIntegration' option.
      ''
      ''
        The 'programs.command-not-found.enable' option is mutually exclusive
        with the 'programs.nix-index.enableZshIntegration' option.
      ''
    ];
  };
}