Add flake checks

checks.nix

@@ -0,0 +1,65 @@
+{
+  self,
+  nixosSystem,
+  pkgs,
+  ...
+}:
+let
+  # A dummy package with no maintainer
+  orphanPkg = pkgs.stdenv.mkDerivation {
+    name = "dummy-unmaintained-package";
+    installPhase = ''
+      echo "dummy-unmaintained-package" > $out
+    '';
+    meta = {
+      maintainers = [ ];
+    };
+  };
+
+  # A dummy package with a maintainer
+  parentPkg = pkgs.stdenv.mkDerivation {
+    name = "dummy-maintained-package";
+    buildInputs = [ orphanPkg ];
+    installPhase = ''
+      echo "dummy-maintained-package" > $out
+    '';
+    meta = {
+      maintainers = [ { github = "github"; } ];
+    };
+  };
+
+  # A dummy NixOS config with an unmaintained package in its closure
+  config = nixosSystem {
+    inherit (pkgs) system;
+    modules = [
+      (
+        { ... }:
+        {
+          environment.systemPackages = [ parentPkg ];
+          # Boilerplate so nixosSystem compiles
+          fileSystems."/" = {
+            device = "/dev/dvd";
+            fsType = "ext4";
+          };
+          boot.loader.grub.device = "/dev/dvd";
+          system.stateVersion = "24.05";
+        }
+      )
+    ];
+  };
+
+  inherit (self.bundlers.${pkgs.system}) all unmaintained;
+
+  grepCheck =
+    name: search: target:
+    pkgs.runCommandLocal name { } ''
+      wc -l ${target} >> test.log
+      grep ${search} ${target} >> test.log
+      cp test.log $out
+    '';
+in
+{
+  package = grepCheck "package" orphanPkg.name (unmaintained orphanPkg);
+  packageClosure = grepCheck "packageClosure" orphanPkg.name (unmaintained parentPkg);
+  configClosure = grepCheck "configClosure" orphanPkg.name (unmaintained config);
+}

flake.nix

@@ -13,12 +13,12 @@
       system = "x86_64-linux";
     in
     {
+      lib = forAllSystems (system: import ./lib.nix { pkgs = nixpkgsFor.${system}; });
+
       bundlers = forAllSystems (
         system:
         let
-          pkgs = nixpkgsFor.${system};
-          lib = import ./lib.nix { inherit pkgs; };
-          inherit (lib) allMaintainers expandInput noMaintainers;
+          inherit (self.lib.${system}) allMaintainers expandInput noMaintainers;
         in
         {
           default = self.bundlers.${system}.unmaintained;
@@ -28,5 +28,14 @@
       );
 
       formatter = forAllSystems (system: nixpkgsFor.${system}.nixfmt-rfc-style);
+
+      checks = forAllSystems (
+        system:
+        import ./checks.nix {
+          inherit self;
+          inherit (nixpkgs.lib) nixosSystem;
+          pkgs = nixpkgsFor.${system};
+        }
+      );
     };
 }

lib.nix

@@ -9,11 +9,7 @@ let
     tail
     ;
   inherit (pkgs) runCommandLocal writeText;
-  inherit (pkgs.lib)
-    concatLines
-    concatStringsSep
-    filter
-    ;
+  inherit (pkgs.lib) concatLines concatStringsSep filter;
   inherit (import ./closure.nix { inherit pkgs; }) drvClosure;
 in
 rec {
@@ -65,10 +61,7 @@ rec {
   expandInput =
     input:
     if (input.class or null == "nixos") && (input._type or null == "configuration") then
-      [
-        input.config.system.build.toplevel
-        input.config.environment.systemPackages
-      ]
+      [ input.config.system.build.toplevel ] ++ input.config.environment.systemPackages
     else
       input;
 }

result

@@ -0,0 +1 @@
+/nix/store/jji7927zp2qx8j5yazg8hj32mgpqlf76-check-nixos-config