tests/platforms: add failing test for #4341

We see infinite recursion when `config.lib` is used to construct or define a `programs.nixvim` module.

tests/platforms/darwin.nix

@@ -14,5 +14,6 @@ self.inputs.nix-darwin.lib.darwinSystem {
       system.stateVersion = 5;
     }
     self.nixDarwinModules.nixvim
+    ./inf-rec-lib.nix
   ];
 }

tests/platforms/hm.nix

@@ -19,5 +19,6 @@ self.inputs.home-manager.lib.homeManagerConfiguration {
       programs.home-manager.enable = true;
     }
     self.homeModules.nixvim
+    ./inf-rec-lib.nix
   ];
 }

tests/platforms/inf-rec-lib.nix

@@ -0,0 +1,7 @@
+# Regression test to ensure `config.lib` can be used to define nixvim modules.
+# This causes infinite recursion if any of `config.lib`'s own definitions depend on `program.nixvim`'s result.
+{ config, ... }:
+{
+  lib.test.nixvimModule = { };
+  programs.nixvim = config.lib.test.nixvimModule;
+}

tests/platforms/nixos.nix

@@ -19,5 +19,6 @@ self.inputs.nixpkgs.lib.nixosSystem {
       };
     }
     self.nixosModules.nixvim
+    ./inf-rec-lib.nix
   ];
 }