Test if packages are loadable with the wrapper

.github/workflows/test.yml

@@ -37,6 +37,8 @@ jobs:
         cd tests && HOME=$(mktemp -d) ../result/bin/emacs -Q --batch \
         --eval "(setq debug-on-error t)" --load init.el
       name: Test if package.el works inside Emacs
-    - run: nix-build --argstr emacsAttr emacs-${{ matrix.attr }} tests
+    - run: |
+        nix-build --argstr emacsAttr emacs-${{ matrix.attr }} tests \
+         && result/bin/test
       if: ${{ ! contains( fromJson('[ "23-4", "24-1", "24-2", "24-3", "24-4", "24-5" ]'), matrix.attr ) }}
-      name: Test low-level Nix usage
+      name: Test if the wrapper builds a configuration

emacs.nix

@@ -91,6 +91,12 @@ stdenv.mkDerivation rec {
 
   installTargets = "tags install";
 
+  # Create site-start.el which is needed by the wrapper
+  postInstall = ''
+    mkdir -p $out/share/emacs/site-lisp
+    touch $out/share/emacs/site-lisp/site-start.el
+  '';
+
   meta = with lib; {
     description = "The extensible, customizable GNU text editor";
     homepage = https://www.gnu.org/software/emacs/;

tests/default.nix

@@ -1,12 +1,28 @@
-{ emacsAttr
-}:
-let
-  pkgs = import (import ../nix/sources.nix).nixpkgs { overlays = [ (import ../overlay.nix) ]; };
-  emacs = (import ../default.nix).${emacsAttr};
+{emacsAttr ? null}: let
+  pkgs = import (import ../nix/sources.nix).nixpkgs {
+    overlays = [(import ../overlay.nix)];
+  };
+  emacs =
+    if emacsAttr == null
+    then pkgs.emacs
+    else (import ../default.nix).${emacsAttr};
 in
-(pkgs.emacsPackagesFor emacs).emacsWithPackages (
-  epkgs: [
-    epkgs.seq
-    epkgs.dash
-  ]
-)
+  pkgs.writeShellApplication {
+    name = "test";
+    runtimeInputs = [
+      ((pkgs.emacs.pkgs.overrideScope' (_: _: {
+          inherit emacs;
+        }))
+        .withPackages (
+          epkgs: [
+            epkgs.seq
+            epkgs.dash
+          ]
+        ))
+    ];
+    text = ''
+      emacs --version
+      emacs -batch -q -l seq -l dash
+      echo "Successfully loaded."
+    '';
+  }