wrapper-manager-fds/lib: init modules subset

lib/default.nix

@@ -22,8 +22,10 @@ pkgs.lib.makeExtensible (
   {
     env = import ./env.nix;
     utils = callLibs ./utils.nix;
+    modules = callLibs ./modules.nix;
 
     inherit (self.env) build eval;
     inherit (self.utils) getBin getLibexec;
+    inherit (self.modules) makeWraparound;
   }
 )

lib/modules.nix

@@ -0,0 +1,52 @@
+# These are functions that are only meant to be invoked inside of a
+# wrapper-manager environment.
+#
+# On a note for wrapper-manager developer(s), due to how tedious it can be to
+# test library functions like that, we're putting them inside of the test
+# configs instead of the typical library test suite.
+{
+  pkgs,
+  lib,
+  self,
+}:
+
+rec {
+  /*
+    Make a wrapper-manager wrapper config containing a sub-wrapper that wraps
+    another program. Several examples of this includes sudo, Bubblewrap, and
+    Gamescope.
+  */
+  makeWraparound = {
+    arg0,
+    under,
+    underFlags ? [ ],
+    underSeparator ? "",
+    ...
+  }@module:
+    let
+      # These are the attrnames that would be overtaken with the function and
+      # will be merged anyways so...
+      functionArgs = builtins.functionArgs makeWraparound;
+      module' = lib.removeAttrs module (lib.attrNames functionArgs);
+    in
+      lib.mkMerge [
+        {
+          arg0 = under;
+
+          # This should be the very first things to be in the arguments so
+          # we're just making sure that it is the case. The priority is chosen
+          # arbitrarily just in case the user already has `prependArgs` values
+          # with `lib.mkBefore` for the original arg0.
+          prependArgs = lib.mkOrder 250 (
+            underFlags
+            ++ lib.optionals (underSeparator != "") [ underSeparator ]
+            ++ [ arg0 ]
+          );
+        }
+
+        # It's constructed like this to make it ergonomic to use. The user can
+        # simply delete the makeWraparound exclusive arguments and still work
+        # normally.
+        module'
+      ];
+}

tests/configs/default.nix

@@ -17,4 +17,5 @@ in
   };
   single-basepackage = build { modules = [ ./single-basepackage.nix ]; };
   neofetch-with-additional-files = build { modules = [ ./neofetch-with-additional-files.nix ]; };
+  lib-modules-make-wraparound = build { modules = [ ./lib-modules-subset/make-wraparound.nix ]; };
 }

tests/configs/lib-modules-subset/make-wraparound.nix

@@ -0,0 +1,26 @@
+{ config, lib, pkgs, wrapperManagerLib, ... }:
+
+let
+  inherit (wrapperManagerLib) makeWraparound;
+in
+{
+  build.variant = "shell";
+  wrappers.tmux = makeWraparound {
+    under = lib.getExe' pkgs.boxxy "boxxy";
+    underFlags = [ "--rule" "~/.tmux.conf:~/.config/tmux/tmux.conf" ];
+    underSeparator = "--";
+
+    arg0 = lib.getExe' pkgs.tmux "tmux";
+  };
+
+  build.extraPassthru.wrapperManagerTests = {
+    actuallyBuilt =
+      let
+        wrapper = config.build.toplevel;
+        tmux = lib.getExe' wrapper "tmux";
+      in
+      pkgs.runCommand "wrapper-manager-tmux-actually-built" { } ''
+        [ -x "${tmux}" ] && touch $out
+      '';
+  };
+}