diff --git a/tests/default.nix b/tests/default.nix
index a773fd50..a6daa4c0 100644
--- a/tests/default.nix
+++ b/tests/default.nix
@@ -26,10 +26,13 @@ let
       # unnecessary rebuilds of the tests.
       manual.manpages.enable = false;
 
-      imports = [ ./asserts.nix ];
+      imports = [ ./asserts.nix ./stubs.nix ];
     }
   ];
 
+  isDarwin = pkgs.stdenv.hostPlatform.isDarwin;
+  isLinux = pkgs.stdenv.hostPlatform.isLinux;
+
 in
 
 import nmt {
@@ -89,12 +92,11 @@ import nmt {
     ./modules/programs/zplug
     ./modules/programs/zsh
     ./modules/xresources
-  ] ++ lib.optionals pkgs.stdenv.hostPlatform.isDarwin [
+  ] ++ lib.optionals isDarwin [
     ./modules/targets-darwin
-  ] ++ lib.optionals pkgs.stdenv.hostPlatform.isLinux [
+  ] ++ lib.optionals isLinux [
     ./modules/config/i18n
     ./modules/i18n/input-method
-    ./modules/misc/debug
     ./modules/misc/gtk
     ./modules/misc/numlock
     ./modules/misc/pam
@@ -103,7 +105,6 @@ import nmt {
     ./modules/misc/xsession
     ./modules/programs/abook
     ./modules/programs/autorandr
-    ./modules/programs/firefox
     ./modules/programs/foot
     ./modules/programs/getmail
     ./modules/programs/gnome-terminal
@@ -142,5 +143,8 @@ import nmt {
     ./modules/targets-linux
   ] ++ lib.optionals enableBig [
     ./modules/programs/emacs
+  ] ++ lib.optionals (enableBig && isLinux) [
+    ./modules/misc/debug
+    ./modules/programs/firefox
   ]);
 }
diff --git a/tests/modules/i18n/input-method/fcitx5-configuration.nix b/tests/modules/i18n/input-method/fcitx5-configuration.nix
index b29a94aa..59738fb0 100644
--- a/tests/modules/i18n/input-method/fcitx5-configuration.nix
+++ b/tests/modules/i18n/input-method/fcitx5-configuration.nix
@@ -1,15 +1,14 @@
 { config, pkgs, ... }:
 
 {
-  config = {
-    nixpkgs.overlays = [ (import ./fcitx5-overlay.nix) ];
-    i18n.inputMethod = {
-      enabled = "fcitx5";
-      fcitx5.addons = with pkgs; [ fcitx5-chinese-addons ];
-    };
+  imports = [ ./fcitx5-stubs.nix ];
 
-    nmt.script = ''
-      assertFileExists home-files/.config/systemd/user/fcitx5-daemon.service
-    '';
+  i18n.inputMethod = {
+    enabled = "fcitx5";
+    fcitx5.addons = with pkgs; [ fcitx5-chinese-addons ];
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/systemd/user/fcitx5-daemon.service
+  '';
 }
diff --git a/tests/modules/i18n/input-method/fcitx5-overlay.nix b/tests/modules/i18n/input-method/fcitx5-overlay.nix
deleted file mode 100644
index 4007552c..00000000
--- a/tests/modules/i18n/input-method/fcitx5-overlay.nix
+++ /dev/null
@@ -1,22 +0,0 @@
-final: prev:
-
-let
-
-  dummy = prev.runCommandLocal "dummy-package" { } "mkdir $out";
-
-in {
-  fcitx5 = prev.runCommandLocal "fcitx5" { version = "0"; } ''
-    mkdir -p $out/bin $out/share/applications $out/etc/xdg/autostart
-    touch $out/bin/fcitx5 \
-          $out/share/applications/org.fcitx.Fcitx5.desktop \
-          $out/etc/xdg/autostart/org.fcitx.Fcitx5.desktop
-    chmod +x $out/bin/fcitx5
-  '';
-  fcitx5-configtool = dummy;
-  fcitx5-lua = dummy;
-  fcitx5-qt = dummy;
-  fcitx5-gtk = dummy;
-  fcitx5-with-addons =
-    prev.fcitx5-with-addons.override { inherit (final) fcitx5-qt; };
-  fcitx5-chinese-addons = dummy;
-}
diff --git a/tests/modules/i18n/input-method/fcitx5-stubs.nix b/tests/modules/i18n/input-method/fcitx5-stubs.nix
new file mode 100644
index 00000000..cdf707de
--- /dev/null
+++ b/tests/modules/i18n/input-method/fcitx5-stubs.nix
@@ -0,0 +1,27 @@
+{
+  test.stubs = {
+    fcitx5 = {
+      version = "0";
+      outPath = null;
+      buildScript = ''
+        mkdir -p $out/bin $out/share/applications $out/etc/xdg/autostart
+        touch $out/bin/fcitx5 \
+              $out/share/applications/org.fcitx.Fcitx5.desktop \
+              $out/etc/xdg/autostart/org.fcitx.Fcitx5.desktop
+        chmod +x $out/bin/fcitx5
+      '';
+    };
+    fcitx5-configtool = { outPath = null; };
+    fcitx5-lua = { outPath = null; };
+    fcitx5-qt = { outPath = null; };
+    fcitx5-gtk = { outPath = null; };
+    fcitx5-chinese-addons = { outPath = null; };
+  };
+
+  nixpkgs.overlays = [
+    (self: super: {
+      fcitx5-with-addons =
+        super.fcitx5-with-addons.override { inherit (self) fcitx5-qt; };
+    })
+  ];
+}
diff --git a/tests/modules/misc/gtk/gtk2-basic-config.nix b/tests/modules/misc/gtk/gtk2-basic-config.nix
index 4ac7299a..a49cc44e 100644
--- a/tests/modules/misc/gtk/gtk2-basic-config.nix
+++ b/tests/modules/misc/gtk/gtk2-basic-config.nix
@@ -9,6 +9,8 @@ with lib;
       gtk2.extraConfig = "gtk-can-change-accels = 1";
     };
 
+    test.stubs.dconf = { };
+
     nmt.script = ''
       assertFileExists home-files/.gtkrc-2.0
       assertFileContent home-files/.gtkrc-2.0 ${
diff --git a/tests/modules/misc/gtk/gtk2-config-file-location.nix b/tests/modules/misc/gtk/gtk2-config-file-location.nix
index 41de2877..a0899838 100644
--- a/tests/modules/misc/gtk/gtk2-config-file-location.nix
+++ b/tests/modules/misc/gtk/gtk2-config-file-location.nix
@@ -7,6 +7,8 @@ with lib;
     gtk.enable = true;
     gtk.gtk2.configLocation = "${config.xdg.configHome}/gtk-2.0/gtkrc";
 
+    test.stubs.dconf = { };
+
     nmt.script = ''
       assertFileExists home-files/.config/gtk-2.0/gtkrc
       assertFileRegex home-path/etc/profile.d/hm-session-vars.sh \
diff --git a/tests/modules/misc/numlock/numlock.nix b/tests/modules/misc/numlock/numlock.nix
index aa468c21..5616de1c 100644
--- a/tests/modules/misc/numlock/numlock.nix
+++ b/tests/modules/misc/numlock/numlock.nix
@@ -6,9 +6,7 @@ with lib;
   config = {
     xsession.numlock.enable = true;
 
-    nixpkgs.overlays = [
-      (self: super: { numlockx = pkgs.writeScriptBin "dummy-numlockx" ""; })
-    ];
+    test.stubs.numlockx = { };
 
     nmt.script = ''
       serviceFile=home-files/.config/systemd/user/numlockx.service
diff --git a/tests/modules/misc/qt/qt-platform-theme-gnome.nix b/tests/modules/misc/qt/qt-platform-theme-gnome.nix
index e9aa1a25..80baeae6 100644
--- a/tests/modules/misc/qt/qt-platform-theme-gnome.nix
+++ b/tests/modules/misc/qt/qt-platform-theme-gnome.nix
@@ -7,15 +7,11 @@
       platformTheme = "gnome";
       style = {
         name = "adwaita";
-        package = pkgs.dummyTheme;
+        package = config.lib.test.mkStubPackage { };
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        dummyTheme = pkgs.runCommandLocal "theme" { } "mkdir $out";
-      })
-    ];
+    test.stubs.qgnomeplatform = { };
 
     nmt.script = ''
       assertFileRegex home-path/etc/profile.d/hm-session-vars.sh \
diff --git a/tests/modules/programs/abook/no-settings.nix b/tests/modules/programs/abook/no-settings.nix
index ad04acd2..f8b096fb 100644
--- a/tests/modules/programs/abook/no-settings.nix
+++ b/tests/modules/programs/abook/no-settings.nix
@@ -6,8 +6,7 @@ with lib;
   config = {
     programs.abook.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { abook = pkgs.writeScriptBin "dummy-abook" ""; }) ];
+    test.stubs.abook = { };
 
     nmt.script = ''
       assertPathNotExists home-files/.config/abook/abookrc
diff --git a/tests/modules/programs/abook/with-settings.nix b/tests/modules/programs/abook/with-settings.nix
index 3cb02a26..e89ad7da 100644
--- a/tests/modules/programs/abook/with-settings.nix
+++ b/tests/modules/programs/abook/with-settings.nix
@@ -28,8 +28,7 @@ with lib;
       '';
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { abook = pkgs.writeScriptBin "dummy-abook" ""; }) ];
+    test.stubs.abook = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/abook/abookrc
diff --git a/tests/modules/programs/alacritty/empty-settings.nix b/tests/modules/programs/alacritty/empty-settings.nix
index 65470473..ecc6df35 100644
--- a/tests/modules/programs/alacritty/empty-settings.nix
+++ b/tests/modules/programs/alacritty/empty-settings.nix
@@ -6,9 +6,7 @@ with lib;
   config = {
     programs.alacritty.enable = true;
 
-    nixpkgs.overlays = [
-      (self: super: { alacritty = pkgs.writeScriptBin "dummy-alacritty" ""; })
-    ];
+    test.stubs.alacritty = { };
 
     nmt.script = ''
       assertPathNotExists home-files/.config/alacritty
diff --git a/tests/modules/programs/alacritty/example-settings.nix b/tests/modules/programs/alacritty/example-settings.nix
index c3671aa0..61b8b4b4 100644
--- a/tests/modules/programs/alacritty/example-settings.nix
+++ b/tests/modules/programs/alacritty/example-settings.nix
@@ -6,7 +6,7 @@ with lib;
   config = {
     programs.alacritty = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-alacritty" "";
+      package = config.lib.test.mkStubPackage { };
 
       settings = {
         window.dimensions = {
diff --git a/tests/modules/programs/alacritty/settings-merging.nix b/tests/modules/programs/alacritty/settings-merging.nix
index 1b8559d6..c7962fb5 100644
--- a/tests/modules/programs/alacritty/settings-merging.nix
+++ b/tests/modules/programs/alacritty/settings-merging.nix
@@ -6,7 +6,7 @@ with lib;
   config = {
     programs.alacritty = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-alacritty" "";
+      package = config.lib.test.mkStubPackage { };
 
       settings = {
         window.dimensions = {
diff --git a/tests/modules/programs/alot/alot.nix b/tests/modules/programs/alot/alot.nix
index 3f74ef21..6316fbd7 100644
--- a/tests/modules/programs/alot/alot.nix
+++ b/tests/modules/programs/alot/alot.nix
@@ -23,8 +23,7 @@ with lib;
 
     programs.alot = { enable = true; };
 
-    nixpkgs.overlays =
-      [ (self: super: { alot = pkgs.writeScriptBin "dummy-alot" ""; }) ];
+    test.stubs.alot = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/alot/config
diff --git a/tests/modules/programs/aria2/settings.nix b/tests/modules/programs/aria2/settings.nix
index 0b5a52d9..346de967 100644
--- a/tests/modules/programs/aria2/settings.nix
+++ b/tests/modules/programs/aria2/settings.nix
@@ -20,8 +20,7 @@ with lib;
       '';
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { aria2 = pkgs.writeScriptBin "dummy-aria2" ""; }) ];
+    test.stubs.aria2 = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/autojump/default-settings.nix b/tests/modules/programs/autojump/default-settings.nix
index 2f667027..2cca7de8 100644
--- a/tests/modules/programs/autojump/default-settings.nix
+++ b/tests/modules/programs/autojump/default-settings.nix
@@ -6,6 +6,10 @@ with lib;
   config = {
     programs.autojump.enable = true;
 
+    test.stubs.autojump = {
+      buildScript = "mkdir -p $out/bin; touch $out/bin/autojump";
+    };
+
     nmt.script = ''
       assertFileExists home-path/bin/autojump
     '';
diff --git a/tests/modules/programs/autorandr/basic-configuration.nix b/tests/modules/programs/autorandr/basic-configuration.nix
index fad18f75..c28edaa2 100644
--- a/tests/modules/programs/autorandr/basic-configuration.nix
+++ b/tests/modules/programs/autorandr/basic-configuration.nix
@@ -28,6 +28,8 @@
       };
     };
 
+    test.stubs.autorandr = { };
+
     nmt.script = ''
       config=home-files/.config/autorandr/default/config
       setup=home-files/.config/autorandr/default/setup
diff --git a/tests/modules/programs/autorandr/scale.nix b/tests/modules/programs/autorandr/scale.nix
index 9092e61d..095778a4 100644
--- a/tests/modules/programs/autorandr/scale.nix
+++ b/tests/modules/programs/autorandr/scale.nix
@@ -17,6 +17,8 @@
       };
     };
 
+    test.stubs.autorandr = { };
+
     nmt.script = ''
       config=home-files/.config/autorandr/default/config
 
diff --git a/tests/modules/programs/bat/bat.nix b/tests/modules/programs/bat/bat.nix
index 2860d1e6..e9861292 100644
--- a/tests/modules/programs/bat/bat.nix
+++ b/tests/modules/programs/bat/bat.nix
@@ -18,8 +18,7 @@ with lib;
       '';
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { bat = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.bat = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/bat/config
diff --git a/tests/modules/programs/bottom/empty-settings.nix b/tests/modules/programs/bottom/empty-settings.nix
index bedcf212..71799c83 100644
--- a/tests/modules/programs/bottom/empty-settings.nix
+++ b/tests/modules/programs/bottom/empty-settings.nix
@@ -6,7 +6,7 @@ with lib;
   config = {
     programs.bottom = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy" "";
+      package = config.lib.test.mkStubPackage { };
     };
 
     nmt.script = ''
diff --git a/tests/modules/programs/bottom/example-settings.nix b/tests/modules/programs/bottom/example-settings.nix
index 3635bd19..30d8e21b 100644
--- a/tests/modules/programs/bottom/example-settings.nix
+++ b/tests/modules/programs/bottom/example-settings.nix
@@ -6,7 +6,7 @@ with lib;
   config = {
     programs.bottom = {
       enable = true;
-      package = pkgs.writeShellScriptBin "dummy" "";
+      package = config.lib.test.mkStubPackage { };
 
       settings = {
         flags = {
diff --git a/tests/modules/programs/broot/broot.nix b/tests/modules/programs/broot/broot.nix
index 88b13974..a2dddca3 100644
--- a/tests/modules/programs/broot/broot.nix
+++ b/tests/modules/programs/broot/broot.nix
@@ -9,8 +9,7 @@ with lib;
       modal = true;
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { broot = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.broot = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/broot/conf.toml
diff --git a/tests/modules/programs/feh/feh-bindings.nix b/tests/modules/programs/feh/feh-bindings.nix
index f6b9e5b6..787b02d7 100644
--- a/tests/modules/programs/feh/feh-bindings.nix
+++ b/tests/modules/programs/feh/feh-bindings.nix
@@ -17,8 +17,7 @@
       prev_img = [ "h" "Left" ];
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { feh = pkgs.writeScriptBin "dummy-feh" ""; }) ];
+    test.stubs.feh = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/feh/feh-empty-settings.nix b/tests/modules/programs/feh/feh-empty-settings.nix
index ad0d1515..62feb823 100644
--- a/tests/modules/programs/feh/feh-empty-settings.nix
+++ b/tests/modules/programs/feh/feh-empty-settings.nix
@@ -4,8 +4,7 @@
   config = {
     programs.feh.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { feh = pkgs.writeScriptBin "dummy-feh" ""; }) ];
+    test.stubs.feh = { };
 
     nmt.script = ''
       assertPathNotExists home-files/.config/feh/buttons
diff --git a/tests/modules/programs/fish/functions.nix b/tests/modules/programs/fish/functions.nix
index 9bca418e..67f8ba0d 100644
--- a/tests/modules/programs/fish/functions.nix
+++ b/tests/modules/programs/fish/functions.nix
@@ -34,8 +34,7 @@ in {
     xdg.dataFile."fish/home-manager_generated_completions".source =
       lib.mkForce (builtins.toFile "empty" "");
 
-    nixpkgs.overlays =
-      [ (self: super: { fish = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.fish = { };
 
     nmt = {
       description =
diff --git a/tests/modules/programs/fish/no-functions.nix b/tests/modules/programs/fish/no-functions.nix
index 7cd2966e..0ab38a09 100644
--- a/tests/modules/programs/fish/no-functions.nix
+++ b/tests/modules/programs/fish/no-functions.nix
@@ -14,8 +14,7 @@ with lib;
     xdg.dataFile."fish/home-manager_generated_completions".source =
       lib.mkForce (builtins.toFile "empty" "");
 
-    nixpkgs.overlays =
-      [ (self: super: { fish = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.fish = { };
 
     nmt = {
       description =
diff --git a/tests/modules/programs/fish/plugins.nix b/tests/modules/programs/fish/plugins.nix
index 61e1603f..6b02dd46 100644
--- a/tests/modules/programs/fish/plugins.nix
+++ b/tests/modules/programs/fish/plugins.nix
@@ -50,8 +50,7 @@ in {
     xdg.dataFile."fish/home-manager_generated_completions".source =
       lib.mkForce (builtins.toFile "empty" "");
 
-    nixpkgs.overlays =
-      [ (self: super: { fish = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.fish = { };
 
     nmt = {
       description =
diff --git a/tests/modules/programs/foot/empty-settings.nix b/tests/modules/programs/foot/empty-settings.nix
index 3935fd9d..26b82e7f 100644
--- a/tests/modules/programs/foot/empty-settings.nix
+++ b/tests/modules/programs/foot/empty-settings.nix
@@ -6,8 +6,7 @@ with lib;
   config = {
     programs.foot.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { foot = pkgs.writeScriptBin "dummy-foot" ""; }) ];
+    test.stubs.foot = { };
 
     nmt.script = ''
       assertPathNotExists home-files/.config/foot
diff --git a/tests/modules/programs/foot/example-settings.nix b/tests/modules/programs/foot/example-settings.nix
index c2306382..8390305e 100644
--- a/tests/modules/programs/foot/example-settings.nix
+++ b/tests/modules/programs/foot/example-settings.nix
@@ -6,7 +6,7 @@ with lib;
   config = {
     programs.foot = {
       enable = true;
-      package = pkgs.writeShellScriptBin "dummy-foot" "";
+      package = config.lib.test.mkStubPackage { };
 
       settings = {
         main = {
diff --git a/tests/modules/programs/foot/systemd-user-service.nix b/tests/modules/programs/foot/systemd-user-service.nix
index 1eff14f9..5ebd9067 100644
--- a/tests/modules/programs/foot/systemd-user-service.nix
+++ b/tests/modules/programs/foot/systemd-user-service.nix
@@ -1,11 +1,9 @@
 { config, lib, pkgs, ... }:
 
-let
-  package = pkgs.writeShellScriptBin "dummy-foot" "" // { outPath = "@foot@"; };
-in {
+{
   config = {
     programs.foot = {
-      inherit package;
+      package = config.lib.test.mkStubPackage { outPath = "@foot@"; };
       enable = true;
       server.enable = true;
     };
diff --git a/tests/modules/programs/gh/config-file.nix b/tests/modules/programs/gh/config-file.nix
index 71fd74d3..432437f9 100644
--- a/tests/modules/programs/gh/config-file.nix
+++ b/tests/modules/programs/gh/config-file.nix
@@ -8,8 +8,7 @@
       editor = "vim";
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { gh = pkgs.writeScriptBin "dummy-gh" ""; }) ];
+    test.stubs.gh = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/gh/config.yml
diff --git a/tests/modules/programs/git/git.nix b/tests/modules/programs/git/git.nix
index 5417f7ea..6c732060 100644
--- a/tests/modules/programs/git/git.nix
+++ b/tests/modules/programs/git/git.nix
@@ -79,14 +79,10 @@ in {
       }
     ];
 
-    nixpkgs.overlays = [
-      (self: super: {
-        git-lfs = pkgs.writeScriptBin "dummy-git-lfs" "";
-        delta = pkgs.writeScriptBin "dummy-delta" "" // {
-          outPath = "@delta@";
-        };
-      })
-    ];
+    test.stubs = {
+      git-lfs = { };
+      delta = { };
+    };
 
     nmt.script = ''
       assertFileExists home-files/.config/git/config
diff --git a/tests/modules/programs/gnome-terminal/gnome-terminal-1.nix b/tests/modules/programs/gnome-terminal/gnome-terminal-1.nix
index 44d95cb3..bb58983f 100644
--- a/tests/modules/programs/gnome-terminal/gnome-terminal-1.nix
+++ b/tests/modules/programs/gnome-terminal/gnome-terminal-1.nix
@@ -4,13 +4,6 @@ with lib;
 
 {
   config = {
-    nixpkgs.overlays = [
-      (self: super: {
-        gnome.gnome-terminal =
-          pkgs.writeScriptBin "dummy-gnome3-gnome-terminal" "";
-      })
-    ];
-
     programs.gnome-terminal = {
       enable = true;
       profile = {
@@ -55,6 +48,14 @@ with lib;
       showMenubar = false;
     };
 
+    nixpkgs.overlays = [
+      (self: super: {
+        gnome.gnome-terminal = config.lib.test.mkStubPackage { };
+      })
+    ];
+
+    test.stubs.dconf = { };
+
     nmt.script = ''
       dconfIni=$(grep -oPm 1 '/nix/store/[a-z0-9]*?-hm-dconf.ini' $TESTED/activate)
       assertFileContent $dconfIni ${./gnome-terminal-1.conf}
diff --git a/tests/modules/programs/himalaya/himalaya.nix b/tests/modules/programs/himalaya/himalaya.nix
index ce5385d1..827a09be 100644
--- a/tests/modules/programs/himalaya/himalaya.nix
+++ b/tests/modules/programs/himalaya/himalaya.nix
@@ -5,34 +5,31 @@ with lib;
 {
   imports = [ ../../accounts/email-test-accounts.nix ];
 
-  config = {
-    accounts.email.accounts = {
-      "hm@example.com" = {
-        himalaya = {
-          enable = true;
+  accounts.email.accounts = {
+    "hm@example.com" = {
+      himalaya = {
+        enable = true;
 
-          settings = { default-page-size = 50; };
-        };
-
-        imap.port = 995;
-        smtp.port = 465;
+        settings = { default-page-size = 50; };
       };
+
+      imap.port = 995;
+      smtp.port = 465;
     };
-
-    programs.himalaya = {
-      enable = true;
-      settings = { downloads-dir = "/data/download"; };
-    };
-
-    nixpkgs.overlays =
-      [ (self: super: { himalaya = pkgs.writeScriptBin "dummy-alot" ""; }) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/himalaya/config.toml
-      assertFileContent home-files/.config/himalaya/config.toml ${
-        ./himalaya-expected.toml
-      }
-    '';
   };
+
+  programs.himalaya = {
+    enable = true;
+    settings = { downloads-dir = "/data/download"; };
+  };
+
+  test.stubs.himalaya = { };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/himalaya/config.toml
+    assertFileContent home-files/.config/himalaya/config.toml ${
+      ./himalaya-expected.toml
+    }
+  '';
 }
 
diff --git a/tests/modules/programs/htop/empty-settings.nix b/tests/modules/programs/htop/empty-settings.nix
index ae4e437f..b8e43600 100644
--- a/tests/modules/programs/htop/empty-settings.nix
+++ b/tests/modules/programs/htop/empty-settings.nix
@@ -6,8 +6,7 @@ with lib;
   config = {
     programs.htop.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { htop = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.htop = { };
 
     nmt.script = ''
       assertPathNotExists home-files/.config/htop
diff --git a/tests/modules/programs/htop/example-settings.nix b/tests/modules/programs/htop/example-settings.nix
index 412b8c7d..71685434 100644
--- a/tests/modules/programs/htop/example-settings.nix
+++ b/tests/modules/programs/htop/example-settings.nix
@@ -36,8 +36,7 @@ with lib;
           (text "Systemd")
         ]);
 
-    nixpkgs.overlays =
-      [ (self: super: { htop = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.htop = { };
 
     nmt.script = ''
       htoprc=home-files/.config/htop/htoprc
diff --git a/tests/modules/programs/htop/settings-without-fields.nix b/tests/modules/programs/htop/settings-without-fields.nix
index 7a6ebe8d..2f4b3e86 100644
--- a/tests/modules/programs/htop/settings-without-fields.nix
+++ b/tests/modules/programs/htop/settings-without-fields.nix
@@ -7,8 +7,7 @@ with lib;
     programs.htop.enable = true;
     programs.htop.settings = { color_scheme = 6; };
 
-    nixpkgs.overlays =
-      [ (self: super: { htop = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.htop = { };
 
     # Test that the 'fields' key is written in addition to the customized
     # settings or htop won't read the options.
diff --git a/tests/modules/programs/i3status-rust/with-custom.nix b/tests/modules/programs/i3status-rust/with-custom.nix
index 4ced6add..b53963dd 100644
--- a/tests/modules/programs/i3status-rust/with-custom.nix
+++ b/tests/modules/programs/i3status-rust/with-custom.nix
@@ -92,11 +92,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        i3status-rust = pkgs.writeScriptBin "dummy-i3status-rust" "";
-      })
-    ];
+    test.stubs.i3status-rust = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/i3status-rust/config-custom.toml
diff --git a/tests/modules/programs/i3status-rust/with-default.nix b/tests/modules/programs/i3status-rust/with-default.nix
index b62c248c..4a0d4a4c 100644
--- a/tests/modules/programs/i3status-rust/with-default.nix
+++ b/tests/modules/programs/i3status-rust/with-default.nix
@@ -6,11 +6,7 @@ with lib;
   config = {
     programs.i3status-rust = { enable = true; };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        i3status-rust = pkgs.writeScriptBin "dummy-i3status-rust" "";
-      })
-    ];
+    test.stubs.i3status-rust = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/i3status-rust/config-default.toml
diff --git a/tests/modules/programs/i3status-rust/with-extra-settings.nix b/tests/modules/programs/i3status-rust/with-extra-settings.nix
index 16f3428a..4a044273 100644
--- a/tests/modules/programs/i3status-rust/with-extra-settings.nix
+++ b/tests/modules/programs/i3status-rust/with-extra-settings.nix
@@ -102,11 +102,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        i3status-rust = pkgs.writeScriptBin "dummy-i3status-rust" "";
-      })
-    ];
+    test.stubs.i3status-rust = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/i3status-rust/config-extra-settings.toml 
diff --git a/tests/modules/programs/i3status-rust/with-multiple-bars.nix b/tests/modules/programs/i3status-rust/with-multiple-bars.nix
index 9cbbe285..eab7f42d 100644
--- a/tests/modules/programs/i3status-rust/with-multiple-bars.nix
+++ b/tests/modules/programs/i3status-rust/with-multiple-bars.nix
@@ -52,11 +52,7 @@ with lib;
 
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        i3status-rust = pkgs.writeScriptBin "dummy-i3status-rust" "";
-      })
-    ];
+    test.stubs.i3status-rust = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/i3status-rust/config-top.toml
diff --git a/tests/modules/programs/i3status/with-custom.nix b/tests/modules/programs/i3status/with-custom.nix
index 4aa01773..830bc6c9 100644
--- a/tests/modules/programs/i3status/with-custom.nix
+++ b/tests/modules/programs/i3status/with-custom.nix
@@ -32,9 +32,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: { i3status = pkgs.writeScriptBin "dummy-i3status" ""; })
-    ];
+    test.stubs.i3status = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/i3status/with-default.nix b/tests/modules/programs/i3status/with-default.nix
index 0b7e4ee2..d56ecc20 100644
--- a/tests/modules/programs/i3status/with-default.nix
+++ b/tests/modules/programs/i3status/with-default.nix
@@ -9,9 +9,7 @@ with lib;
       enableDefault = true;
     };
 
-    nixpkgs.overlays = [
-      (self: super: { i3status = pkgs.writeScriptBin "dummy-i3status" ""; })
-    ];
+    test.stubs.i3status = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/irsii/example-settings.nix b/tests/modules/programs/irsii/example-settings.nix
index d7b9ff1e..0eced168 100644
--- a/tests/modules/programs/irsii/example-settings.nix
+++ b/tests/modules/programs/irsii/example-settings.nix
@@ -19,13 +19,12 @@ with lib;
       };
     };
 
+    test.stubs.irsii = { };
+
     nmt.script = ''
       assertFileContent \
         home-files/.irssi/config \
         ${./example-settings-expected.config}
     '';
-
-    nixpkgs.overlays =
-      [ (self: super: { irsii = pkgs.writeScriptBin "dummy-irsii" ""; }) ];
   };
 }
diff --git a/tests/modules/programs/kitty/example-settings.nix b/tests/modules/programs/kitty/example-settings.nix
index 1f3b82b9..8d609a5a 100644
--- a/tests/modules/programs/kitty/example-settings.nix
+++ b/tests/modules/programs/kitty/example-settings.nix
@@ -30,8 +30,7 @@ with lib;
       environment = { LS_COLORS = "1"; };
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { kitty = pkgs.writeScriptBin "dummy-kitty" ""; }) ];
+    test.stubs.kitty = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/kitty/kitty.conf
diff --git a/tests/modules/programs/lf/all-options.nix b/tests/modules/programs/lf/all-options.nix
index a25467a2..35d7901d 100644
--- a/tests/modules/programs/lf/all-options.nix
+++ b/tests/modules/programs/lf/all-options.nix
@@ -75,8 +75,7 @@ in {
       };
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { lf = pkgs.writeScriptBin "dummy-lf" ""; }) ];
+    test.stubs.lf = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/lf/lfrc
diff --git a/tests/modules/programs/lf/minimal-options.nix b/tests/modules/programs/lf/minimal-options.nix
index b3c26ba9..078c776e 100644
--- a/tests/modules/programs/lf/minimal-options.nix
+++ b/tests/modules/programs/lf/minimal-options.nix
@@ -7,8 +7,7 @@ in {
   config = {
     programs.lf = { enable = true; };
 
-    nixpkgs.overlays =
-      [ (self: super: { lf = pkgs.writeScriptBin "dummy-lf" ""; }) ];
+    test.stubs.lf = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/lf/lfrc
diff --git a/tests/modules/programs/lf/no-pv-keybind.nix b/tests/modules/programs/lf/no-pv-keybind.nix
index 524a41a3..c948cf0b 100644
--- a/tests/modules/programs/lf/no-pv-keybind.nix
+++ b/tests/modules/programs/lf/no-pv-keybind.nix
@@ -32,8 +32,7 @@ in {
       previewer = { source = pvScript; };
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { lf = pkgs.writeScriptBin "dummy-lf" ""; }) ];
+    test.stubs.lf = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/lf/lfrc
diff --git a/tests/modules/programs/lieer/lieer.nix b/tests/modules/programs/lieer/lieer.nix
index c19521d1..5e784746 100644
--- a/tests/modules/programs/lieer/lieer.nix
+++ b/tests/modules/programs/lieer/lieer.nix
@@ -7,7 +7,7 @@ with lib;
 
   config = {
     programs.lieer.enable = true;
-    programs.lieer.package = pkgs.writeScriptBin "dummy-gmailieer" "";
+    programs.lieer.package = config.lib.test.mkStubPackage { };
 
     accounts.email.accounts."hm@example.com" = {
       flavor = "gmail.com";
diff --git a/tests/modules/programs/mangohud/basic-configuration.nix b/tests/modules/programs/mangohud/basic-configuration.nix
index 7ff4a890..6af57d28 100644
--- a/tests/modules/programs/mangohud/basic-configuration.nix
+++ b/tests/modules/programs/mangohud/basic-configuration.nix
@@ -4,7 +4,7 @@
   config = {
     programs.mangohud = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-mangohud" "";
+      package = config.lib.test.mkStubPackage { };
       settings = {
         output_folder = /home/user/Documents/mangohud;
         fps_limit = [ 30 60 ];
diff --git a/tests/modules/programs/mpv/mpv-example-settings.nix b/tests/modules/programs/mpv/mpv-example-settings.nix
index 5701d9ea..9bb53e57 100644
--- a/tests/modules/programs/mpv/mpv-example-settings.nix
+++ b/tests/modules/programs/mpv/mpv-example-settings.nix
@@ -29,9 +29,7 @@
       defaultProfiles = [ "gpu-hq" ];
     };
 
-    nixpkgs.overlays = [
-      (self: super: { mpvDummy = pkgs.runCommandLocal "mpv" { } "mkdir $out"; })
-    ];
+    test.stubs.mpvDummy = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/mpv/mpv-invalid-settings.nix b/tests/modules/programs/mpv/mpv-invalid-settings.nix
index f7fd390a..1c4a80c1 100644
--- a/tests/modules/programs/mpv/mpv-invalid-settings.nix
+++ b/tests/modules/programs/mpv/mpv-invalid-settings.nix
@@ -22,7 +22,7 @@
           touch $out/bin/{,u}mpv $out/Applications/mpv.app/Contents/MacOS/mpv
           chmod 755 $out/bin/{,u}mpv $out/Applications/mpv.app/Contents/MacOS/mpv
         '';
-        mpvDummy = pkgs.runCommandLocal "mpv" { } "mkdir $out";
+        mpvDummy = config.lib.test.mkStubPackage { };
         mpvScript =
           pkgs.runCommandLocal "mpvScript" { scriptName = "something"; }
           "mkdir $out";
diff --git a/tests/modules/programs/ncmpcpp-linux/ncmpcpp-use-mpd-config.nix b/tests/modules/programs/ncmpcpp-linux/ncmpcpp-use-mpd-config.nix
index 5262f031..f977bdde 100644
--- a/tests/modules/programs/ncmpcpp-linux/ncmpcpp-use-mpd-config.nix
+++ b/tests/modules/programs/ncmpcpp-linux/ncmpcpp-use-mpd-config.nix
@@ -7,12 +7,10 @@
     services.mpd.enable = true;
     services.mpd.musicDirectory = "/home/user/music";
 
-    nixpkgs.overlays = [
-      (self: super: {
-        ncmpcpp = pkgs.writeScriptBin "dummy-ncmpcpp" "";
-        mpd = pkgs.writeScriptBin "dummy-mpd" "";
-      })
-    ];
+    test.stubs = {
+      ncmpcpp = { };
+      mpd = { };
+    };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/ncmpcpp/ncmpcpp-empty-settings.nix b/tests/modules/programs/ncmpcpp/ncmpcpp-empty-settings.nix
index e5134002..55436650 100644
--- a/tests/modules/programs/ncmpcpp/ncmpcpp-empty-settings.nix
+++ b/tests/modules/programs/ncmpcpp/ncmpcpp-empty-settings.nix
@@ -4,8 +4,7 @@
   config = {
     programs.ncmpcpp.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { ncmpcpp = pkgs.writeScriptBin "dummy-ncmpcpp" ""; }) ];
+    test.stubs.ncmpcpp = { };
 
     nmt.script = ''
       assertPathNotExists home-files/.config/ncmpcpp/config
diff --git a/tests/modules/programs/ncmpcpp/ncmpcpp-example-settings.nix b/tests/modules/programs/ncmpcpp/ncmpcpp-example-settings.nix
index 02a1f09c..a85ea552 100644
--- a/tests/modules/programs/ncmpcpp/ncmpcpp-example-settings.nix
+++ b/tests/modules/programs/ncmpcpp/ncmpcpp-example-settings.nix
@@ -44,8 +44,7 @@
       ];
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { ncmpcpp = pkgs.writeScriptBin "dummy-ncmpcpp" ""; }) ];
+    test.stubs.ncmpcpp = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/ne/defprefs.nix b/tests/modules/programs/ne/defprefs.nix
index dce98b28..64d78d27 100644
--- a/tests/modules/programs/ne/defprefs.nix
+++ b/tests/modules/programs/ne/defprefs.nix
@@ -19,8 +19,7 @@ in {
       automaticPreferences.".default" = autopref;
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { ne = pkgs.writeScriptBin "dummy-ne" ""; }) ];
+    test.stubs.ne = { };
 
     nmt = {
       description =
diff --git a/tests/modules/programs/ne/passthroughs.nix b/tests/modules/programs/ne/passthroughs.nix
index 4c129e94..f753826f 100644
--- a/tests/modules/programs/ne/passthroughs.nix
+++ b/tests/modules/programs/ne/passthroughs.nix
@@ -53,8 +53,7 @@ in {
       inherit automaticPreferences;
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { ne = pkgs.writeScriptBin "dummy-ne" ""; }) ];
+    test.stubs.ne = { };
 
     nmt = {
       description = "Check that configuration files are correctly written";
diff --git a/tests/modules/programs/neomutt/neomutt-no-folder-change.nix b/tests/modules/programs/neomutt/neomutt-no-folder-change.nix
index db724660..0e874c22 100644
--- a/tests/modules/programs/neomutt/neomutt-no-folder-change.nix
+++ b/tests/modules/programs/neomutt/neomutt-no-folder-change.nix
@@ -17,8 +17,7 @@ with lib;
     programs.neomutt.enable = true;
     programs.neomutt.changeFolderWhenSourcingAccount = false;
 
-    nixpkgs.overlays =
-      [ (self: super: { neomutt = pkgs.writeScriptBin "dummy-neomutt" ""; }) ];
+    test.stubs.neomutt = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/neomutt/hm@example.com
diff --git a/tests/modules/programs/neomutt/neomutt-not-primary.nix b/tests/modules/programs/neomutt/neomutt-not-primary.nix
index 10e9791d..ccf5444a 100644
--- a/tests/modules/programs/neomutt/neomutt-not-primary.nix
+++ b/tests/modules/programs/neomutt/neomutt-not-primary.nix
@@ -13,8 +13,7 @@ with lib;
 
     programs.neomutt.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { neomutt = pkgs.writeScriptBin "dummy-neomutt" ""; }) ];
+    test.stubs.neomutt = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/neomutt/neomuttrc
diff --git a/tests/modules/programs/neomutt/neomutt-with-binds-with-warning.nix b/tests/modules/programs/neomutt/neomutt-with-binds-with-warning.nix
index 529d2847..54012e9d 100644
--- a/tests/modules/programs/neomutt/neomutt-with-binds-with-warning.nix
+++ b/tests/modules/programs/neomutt/neomutt-with-binds-with-warning.nix
@@ -50,8 +50,7 @@ with lib;
       ];
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { neomutt = pkgs.writeScriptBin "dummy-neomutt" ""; }) ];
+    test.stubs.neomutt = { };
 
     test.asserts.warnings.expected = [
       "Specifying 'programs.neomutt.(binds|macros).map' as a string is deprecated, use a list of strings instead. See https://github.com/nix-community/home-manager/pull/1885."
diff --git a/tests/modules/programs/neomutt/neomutt-with-binds.nix b/tests/modules/programs/neomutt/neomutt-with-binds.nix
index bd40cd89..64ebf80f 100644
--- a/tests/modules/programs/neomutt/neomutt-with-binds.nix
+++ b/tests/modules/programs/neomutt/neomutt-with-binds.nix
@@ -50,8 +50,7 @@ with lib;
       ];
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { neomutt = pkgs.writeScriptBin "dummy-neomutt" ""; }) ];
+    test.stubs.neomutt = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/neomutt/neomuttrc
diff --git a/tests/modules/programs/neomutt/neomutt-with-gpg.nix b/tests/modules/programs/neomutt/neomutt-with-gpg.nix
index 164e4b58..2eed5358 100644
--- a/tests/modules/programs/neomutt/neomutt-with-gpg.nix
+++ b/tests/modules/programs/neomutt/neomutt-with-gpg.nix
@@ -16,8 +16,7 @@ with lib; {
 
     programs.neomutt.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { neomutt = pkgs.writeScriptBin "dummy-neomutt" ""; }) ];
+    test.stubs.neomutt = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/neomutt/neomuttrc
diff --git a/tests/modules/programs/neomutt/neomutt-with-msmtp.nix b/tests/modules/programs/neomutt/neomutt-with-msmtp.nix
index 1d5db5f9..48b2197d 100644
--- a/tests/modules/programs/neomutt/neomutt-with-msmtp.nix
+++ b/tests/modules/programs/neomutt/neomutt-with-msmtp.nix
@@ -21,8 +21,7 @@ with lib;
 
     programs.neomutt.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { neomutt = pkgs.writeScriptBin "dummy-neomutt" ""; }) ];
+    test.stubs.neomutt = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/neomutt/neomuttrc
diff --git a/tests/modules/programs/neomutt/neomutt-with-named-mailboxes.nix b/tests/modules/programs/neomutt/neomutt-with-named-mailboxes.nix
index 9478a911..fd4fedf0 100644
--- a/tests/modules/programs/neomutt/neomutt-with-named-mailboxes.nix
+++ b/tests/modules/programs/neomutt/neomutt-with-named-mailboxes.nix
@@ -33,8 +33,7 @@ with lib;
       vimKeys = false;
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { neomutt = pkgs.writeScriptBin "dummy-neomutt" ""; }) ];
+    test.stubs.neomutt = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/neomutt/neomuttrc
diff --git a/tests/modules/programs/neomutt/neomutt.nix b/tests/modules/programs/neomutt/neomutt.nix
index d4419d93..08c8f5bf 100644
--- a/tests/modules/programs/neomutt/neomutt.nix
+++ b/tests/modules/programs/neomutt/neomutt.nix
@@ -24,8 +24,7 @@ with lib;
       vimKeys = false;
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { neomutt = pkgs.writeScriptBin "dummy-neomutt" ""; }) ];
+    test.stubs.neomutt = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/neomutt/neomuttrc
diff --git a/tests/modules/programs/newsboat/newsboat-basics-2003.nix b/tests/modules/programs/newsboat/newsboat-basics-2003.nix
index 587a31bb..26d5f4b3 100644
--- a/tests/modules/programs/newsboat/newsboat-basics-2003.nix
+++ b/tests/modules/programs/newsboat/newsboat-basics-2003.nix
@@ -22,9 +22,7 @@ with lib;
       queries = { "foo" = ''rssurl =~ "example.com"''; };
     };
 
-    nixpkgs.overlays = [
-      (self: super: { newsboat = pkgs.writeScriptBin "dummy-newsboat" ""; })
-    ];
+    test.stubs.newsboat = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/newsboat/newsboat-basics-2105.nix b/tests/modules/programs/newsboat/newsboat-basics-2105.nix
index e7a17c5d..ec0f3372 100644
--- a/tests/modules/programs/newsboat/newsboat-basics-2105.nix
+++ b/tests/modules/programs/newsboat/newsboat-basics-2105.nix
@@ -22,9 +22,7 @@ with lib;
       queries = { "foo" = ''rssurl =~ "example.com"''; };
     };
 
-    nixpkgs.overlays = [
-      (self: super: { newsboat = pkgs.writeScriptBin "dummy-newsboat" ""; })
-    ];
+    test.stubs.newsboat = { };
 
     # The format didn't change since 20.03, just the location.
     nmt.script = ''
diff --git a/tests/modules/programs/newsboat/newsboat-basics.nix b/tests/modules/programs/newsboat/newsboat-basics.nix
index e6eb4151..fe7f8507 100644
--- a/tests/modules/programs/newsboat/newsboat-basics.nix
+++ b/tests/modules/programs/newsboat/newsboat-basics.nix
@@ -20,9 +20,7 @@ with lib;
       queries = { "foo" = ''rssurl =~ "example.com"''; };
     };
 
-    nixpkgs.overlays = [
-      (self: super: { newsboat = pkgs.writeScriptBin "dummy-newsboat" ""; })
-    ];
+    test.stubs.newsboat = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/nix-index/assert-on-command-not-found.nix b/tests/modules/programs/nix-index/assert-on-command-not-found.nix
index b3b869cb..0fa6ee79 100644
--- a/tests/modules/programs/nix-index/assert-on-command-not-found.nix
+++ b/tests/modules/programs/nix-index/assert-on-command-not-found.nix
@@ -12,14 +12,10 @@
     xdg.dataFile."fish/home-manager_generated_completions".source =
       lib.mkForce (builtins.toFile "empty" "");
 
-    nixpkgs.overlays = [
-      (self: super:
-        let dummy = pkgs.writeScriptBin "dummy" "";
-        in {
-          zsh = dummy;
-          fish = dummy;
-        })
-    ];
+    test.stubs = {
+      zsh = { };
+      fish = { };
+    };
 
     programs.nix-index.enable = true;
 
diff --git a/tests/modules/programs/nix-index/integrations.nix b/tests/modules/programs/nix-index/integrations.nix
index 33a5de2d..1ae46df5 100644
--- a/tests/modules/programs/nix-index/integrations.nix
+++ b/tests/modules/programs/nix-index/integrations.nix
@@ -16,14 +16,10 @@ in {
     xdg.dataFile."fish/home-manager_generated_completions".source =
       lib.mkForce (builtins.toFile "empty" "");
 
-    nixpkgs.overlays = [
-      (self: super:
-        let dummy = pkgs.writeScriptBin "dummy" "";
-        in {
-          zsh = dummy;
-          fish = dummy;
-        })
-    ];
+    test.stubs = {
+      zsh = { };
+      fish = { };
+    };
 
     programs.nix-index.enable = true;
 
diff --git a/tests/modules/programs/nushell/settings.nix b/tests/modules/programs/nushell/settings.nix
index 09c192b3..7eef0909 100644
--- a/tests/modules/programs/nushell/settings.nix
+++ b/tests/modules/programs/nushell/settings.nix
@@ -22,8 +22,7 @@ with lib;
       ];
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { nushell = pkgs.writeScriptBin "dummy-nushell" ""; }) ];
+    test.stubs.nushell = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/powerline-go/bash.nix b/tests/modules/programs/powerline-go/bash.nix
index 945bde73..34017d88 100644
--- a/tests/modules/programs/powerline-go/bash.nix
+++ b/tests/modules/programs/powerline-go/bash.nix
@@ -18,8 +18,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { powerline-go = pkgs.writeScriptBin "dummy-pkg" ""; }) ];
+    test.stubs.powerline-go = { };
 
     nmt.script = ''
       assertFileExists home-files/.bashrc
diff --git a/tests/modules/programs/powerline-go/fish.nix b/tests/modules/programs/powerline-go/fish.nix
index 7009c8c2..b7891bbf 100644
--- a/tests/modules/programs/powerline-go/fish.nix
+++ b/tests/modules/programs/powerline-go/fish.nix
@@ -22,14 +22,10 @@ with lib;
     xdg.dataFile."fish/home-manager_generated_completions".source =
       mkForce (builtins.toFile "empty" "");
 
-    nixpkgs.overlays = [
-      (self: super:
-        let dummy = pkgs.writeScriptBin "dummy" "";
-        in {
-          powerline-go = dummy;
-          fish = dummy;
-        })
-    ];
+    test.stubs = {
+      powerline-go = { };
+      fish = { };
+    };
 
     nmt.script = ''
       assertFileExists home-files/.config/fish/config.fish
diff --git a/tests/modules/programs/powerline-go/zsh.nix b/tests/modules/programs/powerline-go/zsh.nix
index 0ed88215..161499c9 100644
--- a/tests/modules/programs/powerline-go/zsh.nix
+++ b/tests/modules/programs/powerline-go/zsh.nix
@@ -18,12 +18,10 @@ with lib;
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        powerline-go = pkgs.writeScriptBin "dummy-pkg" "";
-        zsh = pkgs.writeScriptBin "dummy-pkg" "";
-      })
-    ];
+    test.stubs = {
+      powerline-go = { };
+      zsh = { };
+    };
 
     nmt.script = ''
       assertFileExists home-files/.zshrc
diff --git a/tests/modules/programs/qutebrowser/keybindings.nix b/tests/modules/programs/qutebrowser/keybindings.nix
index 1236c058..a719d9f7 100644
--- a/tests/modules/programs/qutebrowser/keybindings.nix
+++ b/tests/modules/programs/qutebrowser/keybindings.nix
@@ -18,11 +18,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        qutebrowser = pkgs.writeScriptBin "dummy-qutebrowser" "";
-      })
-    ];
+    test.stubs.qutebrowser = { };
 
     nmt.script = let
       qutebrowserConfig = if pkgs.stdenv.hostPlatform.isDarwin then
diff --git a/tests/modules/programs/qutebrowser/quickmarks.nix b/tests/modules/programs/qutebrowser/quickmarks.nix
index 30d1856c..1491a1e6 100644
--- a/tests/modules/programs/qutebrowser/quickmarks.nix
+++ b/tests/modules/programs/qutebrowser/quickmarks.nix
@@ -13,11 +13,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        qutebrowser = pkgs.writeScriptBin "dummy-qutebrowser" "";
-      })
-    ];
+    test.stubs.qutebrowser = { };
 
     nmt.script = let
       quickmarksFile = if pkgs.stdenv.hostPlatform.isDarwin then
diff --git a/tests/modules/programs/qutebrowser/settings.nix b/tests/modules/programs/qutebrowser/settings.nix
index e9bedcaa..dca6ae6f 100644
--- a/tests/modules/programs/qutebrowser/settings.nix
+++ b/tests/modules/programs/qutebrowser/settings.nix
@@ -24,11 +24,7 @@ with lib;
       '';
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        qutebrowser = pkgs.writeScriptBin "dummy-qutebrowser" "";
-      })
-    ];
+    test.stubs.qutebrowser = { };
 
     nmt.script = let
       qutebrowserConfig = if pkgs.stdenv.hostPlatform.isDarwin then
diff --git a/tests/modules/programs/rbw/empty-settings.nix b/tests/modules/programs/rbw/empty-settings.nix
index 3e4c821d..aa25c876 100644
--- a/tests/modules/programs/rbw/empty-settings.nix
+++ b/tests/modules/programs/rbw/empty-settings.nix
@@ -1,4 +1,5 @@
 { pkgs, ... }:
+
 let
   inherit (pkgs.stdenv.hostPlatform) isDarwin;
 
@@ -7,13 +8,11 @@ let
   else
     ".config/rbw/config.json";
 in {
-  config = {
-    programs.rbw.enable = true;
+  imports = [ ./rbw-stubs.nix ];
 
-    nixpkgs.overlays = [ (import ./overlay.nix) ];
+  programs.rbw.enable = true;
 
-    nmt.script = ''
-      assertPathNotExists home-files/${path}
-    '';
-  };
+  nmt.script = ''
+    assertPathNotExists home-files/${path}
+  '';
 }
diff --git a/tests/modules/programs/rbw/overlay.nix b/tests/modules/programs/rbw/overlay.nix
deleted file mode 100644
index f10b1955..00000000
--- a/tests/modules/programs/rbw/overlay.nix
+++ /dev/null
@@ -1,12 +0,0 @@
-self: super: {
-  rbw = self.writeScriptBin "dummy-rbw" "";
-  pinentry = {
-    gnome3 = self.writeScriptBin "pinentry-gnome3" "" // {
-      outPath = "@pinentry-gnome3@";
-    };
-    gtk2 = self.writeScriptBin "pinentry-gtk2" "" // {
-      outPath = "@pinentry-gtk2@";
-    };
-    flavors = [ "gnome3" "gtk2" ];
-  };
-}
diff --git a/tests/modules/programs/rbw/rbw-stubs.nix b/tests/modules/programs/rbw/rbw-stubs.nix
new file mode 100644
index 00000000..c48d88be
--- /dev/null
+++ b/tests/modules/programs/rbw/rbw-stubs.nix
@@ -0,0 +1,16 @@
+{ config, ... }:
+
+{
+  test.stubs.rbw = { };
+
+  nixpkgs.overlays = [
+    (self: super: {
+      pinentry = {
+        gnome3 =
+          config.lib.test.mkStubPackage { outPath = "@pinentry-gnome3@"; };
+        gtk2 = config.lib.test.mkStubPackage { outPath = "@pinentry-gtk2@"; };
+        flavors = [ "gnome3" "gtk2" ];
+      };
+    })
+  ];
+}
diff --git a/tests/modules/programs/rbw/settings.nix b/tests/modules/programs/rbw/settings.nix
index de08ec83..8cf9572b 100644
--- a/tests/modules/programs/rbw/settings.nix
+++ b/tests/modules/programs/rbw/settings.nix
@@ -1,4 +1,5 @@
 { pkgs, ... }:
+
 let
   inherit (pkgs.stdenv.hostPlatform) isDarwin;
 
@@ -17,23 +18,21 @@ let
     }
   '';
 in {
-  config = {
-    programs.rbw = {
-      enable = true;
-      settings = {
-        email = "name@example.com";
-        base_url = "bitwarden.example.com";
-        identity_url = "identity.example.com";
-        lock_timeout = 300;
-        pinentry = "gnome3";
-      };
+  imports = [ ./rbw-stubs.nix ];
+
+  programs.rbw = {
+    enable = true;
+    settings = {
+      email = "name@example.com";
+      base_url = "bitwarden.example.com";
+      identity_url = "identity.example.com";
+      lock_timeout = 300;
+      pinentry = "gnome3";
     };
-
-    nixpkgs.overlays = [ (import ./overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/${path}
-      assertFileContent home-files/${path} '${expected}'
-    '';
   };
+
+  nmt.script = ''
+    assertFileExists home-files/${path}
+    assertFileContent home-files/${path} '${expected}'
+  '';
 }
diff --git a/tests/modules/programs/rbw/simple-settings.nix b/tests/modules/programs/rbw/simple-settings.nix
index 4e05b69f..becf9fad 100644
--- a/tests/modules/programs/rbw/simple-settings.nix
+++ b/tests/modules/programs/rbw/simple-settings.nix
@@ -1,4 +1,5 @@
 { pkgs, ... }:
+
 let
   inherit (pkgs.stdenv.hostPlatform) isDarwin;
 
@@ -17,17 +18,15 @@ let
     }
   '';
 in {
-  config = {
-    programs.rbw = {
-      enable = true;
-      settings = { email = "name@example.com"; };
-    };
+  imports = [ ./rbw-stubs.nix ];
 
-    nixpkgs.overlays = [ (import ./overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/${path}
-      assertFileContent home-files/${path} '${expected}'
-    '';
+  programs.rbw = {
+    enable = true;
+    settings = { email = "name@example.com"; };
   };
+
+  nmt.script = ''
+    assertFileExists home-files/${path}
+    assertFileContent home-files/${path} '${expected}'
+  '';
 }
diff --git a/tests/modules/programs/rofi-pass/rofi-pass-config.nix b/tests/modules/programs/rofi-pass/rofi-pass-config.nix
index a1161dbd..2028e840 100644
--- a/tests/modules/programs/rofi-pass/rofi-pass-config.nix
+++ b/tests/modules/programs/rofi-pass/rofi-pass-config.nix
@@ -16,14 +16,10 @@ with lib;
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super:
-        let dummy = pkgs.writeScriptBin "dummy" "";
-        in {
-          rofi = dummy;
-          rofi-pass = dummy;
-        })
-    ];
+    test.stubs = {
+      rofi = { };
+      rofi-pass = { };
+    };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/rofi-pass/rofi-pass-root.nix b/tests/modules/programs/rofi-pass/rofi-pass-root.nix
index 02bd06c1..300e89db 100644
--- a/tests/modules/programs/rofi-pass/rofi-pass-root.nix
+++ b/tests/modules/programs/rofi-pass/rofi-pass-root.nix
@@ -13,14 +13,10 @@ with lib;
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super:
-        let dummy = pkgs.writeScriptBin "dummy" "";
-        in {
-          rofi = dummy;
-          rofi-pass = dummy;
-        })
-    ];
+    test.stubs = {
+      rofi = { };
+      rofi-pass = { };
+    };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/rofi/assert-on-both-theme-and-colors.nix b/tests/modules/programs/rofi/assert-on-both-theme-and-colors.nix
index 087ca472..a62faf73 100644
--- a/tests/modules/programs/rofi/assert-on-both-theme-and-colors.nix
+++ b/tests/modules/programs/rofi/assert-on-both-theme-and-colors.nix
@@ -17,8 +17,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { rofi = pkgs.writeScriptBin "dummy-rofi" ""; }) ];
+    test.stubs.rofi = { };
 
     test.asserts.assertions.expected = [''
       Cannot use the rofi options 'theme' and 'colors' simultaneously.
diff --git a/tests/modules/programs/rofi/custom-theme.nix b/tests/modules/programs/rofi/custom-theme.nix
index 2d318a4e..99c9a989 100644
--- a/tests/modules/programs/rofi/custom-theme.nix
+++ b/tests/modules/programs/rofi/custom-theme.nix
@@ -29,8 +29,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { rofi = pkgs.writeScriptBin "dummy-rofi" ""; }) ];
+    test.stubs.rofi = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/rofi/valid-config.nix b/tests/modules/programs/rofi/valid-config.nix
index efcb1acd..84c74152 100644
--- a/tests/modules/programs/rofi/valid-config.nix
+++ b/tests/modules/programs/rofi/valid-config.nix
@@ -48,8 +48,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { rofi = pkgs.writeScriptBin "dummy-rofi" ""; }) ];
+    test.stubs.rofi = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/scmpuff/no-shell.nix b/tests/modules/programs/scmpuff/no-shell.nix
index 96314e7a..ddc40773 100644
--- a/tests/modules/programs/scmpuff/no-shell.nix
+++ b/tests/modules/programs/scmpuff/no-shell.nix
@@ -10,8 +10,7 @@
       zsh.enable = true;
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { zsh = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.zsh = { };
 
     nmt.script = ''
       assertFileNotRegex home-files/.zshrc '${pkgs.scmpuff} init -s'
diff --git a/tests/modules/programs/scmpuff/no-zsh.nix b/tests/modules/programs/scmpuff/no-zsh.nix
index 90e0034b..5854fdd6 100644
--- a/tests/modules/programs/scmpuff/no-zsh.nix
+++ b/tests/modules/programs/scmpuff/no-zsh.nix
@@ -8,8 +8,7 @@
       zsh.enable = true;
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { zsh = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.zsh = { };
 
     nmt.script = ''
       assertFileNotRegex home-files/.zshrc '${pkgs.scmpuff} init -s'
diff --git a/tests/modules/programs/scmpuff/zsh.nix b/tests/modules/programs/scmpuff/zsh.nix
index b27f6ca8..d132945f 100644
--- a/tests/modules/programs/scmpuff/zsh.nix
+++ b/tests/modules/programs/scmpuff/zsh.nix
@@ -5,8 +5,7 @@
       zsh.enable = true;
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { zsh = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.zsh = { };
 
     nmt.script = ''
       assertFileExists home-files/.zshrc
diff --git a/tests/modules/programs/sm64ex/settings.nix b/tests/modules/programs/sm64ex/settings.nix
index 9ccf3953..04499f15 100644
--- a/tests/modules/programs/sm64ex/settings.nix
+++ b/tests/modules/programs/sm64ex/settings.nix
@@ -39,8 +39,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { sm64ex = pkgs.writeScriptBin "dummy-sm64ex" ""; }) ];
+    test.stubs.sm64ex = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/starship/settings.nix b/tests/modules/programs/starship/settings.nix
index 4c506c9e..c3517cae 100644
--- a/tests/modules/programs/starship/settings.nix
+++ b/tests/modules/programs/starship/settings.nix
@@ -44,9 +44,7 @@ with lib;
       ];
     };
 
-    nixpkgs.overlays = [
-      (self: super: { starship = pkgs.writeScriptBin "dummy-starship" ""; })
-    ];
+    test.stubs.starship = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/terminator/config-file.nix b/tests/modules/programs/terminator/config-file.nix
index 1ae06fdc..50b9c42e 100644
--- a/tests/modules/programs/terminator/config-file.nix
+++ b/tests/modules/programs/terminator/config-file.nix
@@ -8,8 +8,7 @@
       };
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { terminator = pkgs.writeScriptBin "dummy" ""; }) ];
+    test.stubs.terminator = { };
 
     nmt.script = ''
       assertFileContent home-files/.config/terminator/config ${
diff --git a/tests/modules/programs/topgrade/settings.nix b/tests/modules/programs/topgrade/settings.nix
index a7436b5e..a8f5c6d1 100644
--- a/tests/modules/programs/topgrade/settings.nix
+++ b/tests/modules/programs/topgrade/settings.nix
@@ -25,9 +25,7 @@ with lib;
       ];
     };
 
-    nixpkgs.overlays = [
-      (self: super: { topgrade = pkgs.writeScriptBin "dummy-topgrade" ""; })
-    ];
+    test.stubs.topgrade = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/programs/waybar/settings-complex.nix b/tests/modules/programs/waybar/settings-complex.nix
index 1756ae12..1297f557 100644
--- a/tests/modules/programs/waybar/settings-complex.nix
+++ b/tests/modules/programs/waybar/settings-complex.nix
@@ -2,12 +2,10 @@
 
 with lib;
 
-let
-  package = pkgs.writeScriptBin "dummy-waybar" "" // { outPath = "@waybar@"; };
-in {
+{
   config = {
     programs.waybar = {
-      inherit package;
+      package = config.lib.test.mkStubPackage { outPath = "@waybar@"; };
       enable = true;
       settings = [{
         layer = "top";
@@ -41,9 +39,7 @@ in {
             format = "hello from {}";
             exec = let
               dummyScript =
-                pkgs.writeShellScriptBin "dummy" "echo within waybar" // {
-                  outPath = "@dummy@";
-                };
+                config.lib.test.mkStubPackage { outPath = "@dummy@"; };
             in "${dummyScript}/bin/dummy";
           };
         };
diff --git a/tests/modules/programs/waybar/styling.nix b/tests/modules/programs/waybar/styling.nix
index bd73f2aa..6e34847e 100644
--- a/tests/modules/programs/waybar/styling.nix
+++ b/tests/modules/programs/waybar/styling.nix
@@ -2,12 +2,10 @@
 
 with lib;
 
-let
-  package = pkgs.writeScriptBin "dummy-waybar" "" // { outPath = "@waybar@"; };
-in {
+{
   config = {
     programs.waybar = {
-      inherit package;
+      package = config.lib.test.mkStubPackage { outPath = "@waybar@"; };
       enable = true;
       style = ''
         * {
diff --git a/tests/modules/programs/waybar/systemd-with-graphical-session-target.nix b/tests/modules/programs/waybar/systemd-with-graphical-session-target.nix
index e751d804..eff5af9c 100644
--- a/tests/modules/programs/waybar/systemd-with-graphical-session-target.nix
+++ b/tests/modules/programs/waybar/systemd-with-graphical-session-target.nix
@@ -2,12 +2,10 @@
 
 with lib;
 
-let
-  package = pkgs.writeScriptBin "dummy-waybar" "" // { outPath = "@waybar@"; };
-in {
+{
   config = {
     programs.waybar = {
-      inherit package;
+      package = config.lib.test.mkStubPackage { outPath = "@waybar@"; };
       enable = true;
       systemd.enable = true;
     };
diff --git a/tests/modules/programs/waybar/warnings-tests.nix b/tests/modules/programs/waybar/warnings-tests.nix
index f7912dba..e844cc61 100644
--- a/tests/modules/programs/waybar/warnings-tests.nix
+++ b/tests/modules/programs/waybar/warnings-tests.nix
@@ -2,12 +2,10 @@
 
 with lib;
 
-let
-  package = pkgs.writeScriptBin "dummy-waybar" "" // { outPath = "@waybar@"; };
-in {
+{
   config = {
     programs.waybar = {
-      inherit package;
+      package = config.lib.test.mkStubPackage { outPath = "@waybar@"; };
       enable = true;
       settings = [{
         modules-left = [ "custom/my-module" ];
diff --git a/tests/modules/programs/xmobar/basic-configuration.nix b/tests/modules/programs/xmobar/basic-configuration.nix
index 99ed57de..bbd9420e 100644
--- a/tests/modules/programs/xmobar/basic-configuration.nix
+++ b/tests/modules/programs/xmobar/basic-configuration.nix
@@ -6,7 +6,7 @@ with lib;
   config = {
     programs.xmobar = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy" "";
+      package = config.lib.test.mkStubPackage { };
       extraConfig = ''
         Config
           { font        = "Fira Code"
diff --git a/tests/modules/programs/zplug/modules.nix b/tests/modules/programs/zplug/modules.nix
index 704c5c5e..373b6b88 100644
--- a/tests/modules/programs/zplug/modules.nix
+++ b/tests/modules/programs/zplug/modules.nix
@@ -21,16 +21,14 @@ with lib;
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        zsh = pkgs.writeScriptBin "dummy-zsh" "";
-        zplug = pkgs.writeScriptBin "dummy-zplug" "";
-      })
-    ];
+    test.stubs = {
+      zplug = { };
+      zsh = { };
+    };
 
     nmt.script = ''
-      assertFileRegex home-files/.zshrc \
-        '^source ${builtins.storeDir}/.*zplug.*/init\.zsh$'
+      assertFileContains home-files/.zshrc \
+        'source @zplug@/init.zsh'
 
       assertFileContains home-files/.zshrc \
         'zplug "plugins/git", from:oh-my-zsh'
diff --git a/tests/modules/programs/zsh/history-ignore-pattern.nix b/tests/modules/programs/zsh/history-ignore-pattern.nix
index ba423efe..68be58fe 100644
--- a/tests/modules/programs/zsh/history-ignore-pattern.nix
+++ b/tests/modules/programs/zsh/history-ignore-pattern.nix
@@ -11,8 +11,7 @@ with lib;
   config = {
     programs.zsh.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { zsh = pkgs.writeScriptBin "dummy-zsh" ""; }) ];
+    test.stubs.zsh = { };
 
     nmt.script = ''
       assertFileContains home-files/.zshrc "HISTORY_IGNORE='(echo *|rm *)'"
diff --git a/tests/modules/programs/zsh/history-path-new-custom.nix b/tests/modules/programs/zsh/history-path-new-custom.nix
index 0c052d69..1a691f1c 100644
--- a/tests/modules/programs/zsh/history-path-new-custom.nix
+++ b/tests/modules/programs/zsh/history-path-new-custom.nix
@@ -10,8 +10,7 @@ with lib;
       history.path = "$HOME/some/directory/zsh_history";
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { zsh = pkgs.writeScriptBin "dummy-zsh" ""; }) ];
+    test.stubs.zsh = { };
 
     nmt.script = ''
       assertFileRegex home-files/.zshrc '^HISTFILE="$HOME/some/directory/zsh_history"$'
diff --git a/tests/modules/programs/zsh/history-path-new-default.nix b/tests/modules/programs/zsh/history-path-new-default.nix
index 6d1f58a2..06fe88d0 100644
--- a/tests/modules/programs/zsh/history-path-new-default.nix
+++ b/tests/modules/programs/zsh/history-path-new-default.nix
@@ -7,8 +7,7 @@ with lib;
     home.stateVersion = "20.03";
     programs.zsh.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { zsh = pkgs.writeScriptBin "dummy-zsh" ""; }) ];
+    test.stubs.zsh = { };
 
     nmt.script = ''
       assertFileRegex home-files/.zshrc '^HISTFILE="$HOME/.zsh_history"$'
diff --git a/tests/modules/programs/zsh/history-path-old-custom.nix b/tests/modules/programs/zsh/history-path-old-custom.nix
index f5b178b5..42a85d00 100644
--- a/tests/modules/programs/zsh/history-path-old-custom.nix
+++ b/tests/modules/programs/zsh/history-path-old-custom.nix
@@ -10,8 +10,7 @@ with lib;
       history.path = "some/directory/zsh_history";
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { zsh = pkgs.writeScriptBin "dummy-zsh" ""; }) ];
+    test.stubs.zsh = { };
 
     nmt.script = ''
       assertFileRegex home-files/.zshrc '^HISTFILE="$HOME/some/directory/zsh_history"$'
diff --git a/tests/modules/programs/zsh/history-path-old-default.nix b/tests/modules/programs/zsh/history-path-old-default.nix
index d880d966..490a2715 100644
--- a/tests/modules/programs/zsh/history-path-old-default.nix
+++ b/tests/modules/programs/zsh/history-path-old-default.nix
@@ -7,8 +7,7 @@ with lib;
     home.stateVersion = "19.03";
     programs.zsh.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { zsh = pkgs.writeScriptBin "dummy-zsh" ""; }) ];
+    test.stubs.zsh = { };
 
     nmt.script = ''
       assertFileRegex home-files/.zshrc '^HISTFILE="$HOME/.zsh_history"$'
diff --git a/tests/modules/programs/zsh/prezto.nix b/tests/modules/programs/zsh/prezto.nix
index 5bc95510..922112ef 100644
--- a/tests/modules/programs/zsh/prezto.nix
+++ b/tests/modules/programs/zsh/prezto.nix
@@ -3,23 +3,20 @@
 with lib;
 
 {
-  config = {
-    programs.zsh.prezto.enable = true;
+  programs.zsh.prezto.enable = true;
 
-    nixpkgs.overlays = [
-      (self: super: {
-        zsh-prezto = super.runCommandLocal "dummy-zsh-prezto" { } ''
-          mkdir -p $out/share/zsh-prezto/runcoms
-          echo '# zprofile' > $out/share/zsh-prezto/runcoms/zprofile
-          echo '# zlogin' > $out/share/zsh-prezto/runcoms/zlogin
-          echo '# zlogout' > $out/share/zsh-prezto/runcoms/zlogout
-          echo '# zshenv' > $out/share/zsh-prezto/runcoms/zshenv
-        '';
-      })
-    ];
-
-    nmt.script = ''
-      assertFileExists home-files/.zpreztorc
+  test.stubs.zsh-prezto = {
+    outPath = null;
+    buildScript = ''
+      mkdir -p $out/share/zsh-prezto/runcoms
+      echo '# zprofile' > $out/share/zsh-prezto/runcoms/zprofile
+      echo '# zlogin' > $out/share/zsh-prezto/runcoms/zlogin
+      echo '# zlogout' > $out/share/zsh-prezto/runcoms/zlogout
+      echo '# zshenv' > $out/share/zsh-prezto/runcoms/zshenv
     '';
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.zpreztorc
+  '';
 }
diff --git a/tests/modules/programs/zsh/session-variables.nix b/tests/modules/programs/zsh/session-variables.nix
index 5c322be1..638b41c9 100644
--- a/tests/modules/programs/zsh/session-variables.nix
+++ b/tests/modules/programs/zsh/session-variables.nix
@@ -13,8 +13,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { zsh = pkgs.writeScriptBin "dummy-zsh" ""; }) ];
+    test.stubs.zsh = { };
 
     nmt.script = ''
       assertFileExists home-files/.zshrc
diff --git a/tests/modules/services/barrier/basic-configuration.nix b/tests/modules/services/barrier/basic-configuration.nix
index 83a9365e..03b1beae 100644
--- a/tests/modules/services/barrier/basic-configuration.nix
+++ b/tests/modules/services/barrier/basic-configuration.nix
@@ -7,8 +7,7 @@
       server = "testServer";
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { barrier = pkgs.writeScriptBin "dummy-barrier" ""; }) ];
+    test.stubs.barrier = { };
 
     nmt.script = ''
       clientServiceFile=home-files/.config/systemd/user/barrierc.service
diff --git a/tests/modules/services/devilspie2/configuration.nix b/tests/modules/services/devilspie2/configuration.nix
index eb576b9f..2072d4d8 100644
--- a/tests/modules/services/devilspie2/configuration.nix
+++ b/tests/modules/services/devilspie2/configuration.nix
@@ -18,9 +18,7 @@
       '';
     };
 
-    nixpkgs.overlays = [
-      (self: super: { devilspie2 = pkgs.writeScriptBin "dummy-devilspie2" ""; })
-    ];
+    test.stubs.devilspie2 = { };
 
     nmt.script = ''
       configlua=home-files/.config/devilspie2/config.lua
diff --git a/tests/modules/services/dropbox/basic-configuration.nix b/tests/modules/services/dropbox/basic-configuration.nix
index 96a17cd7..9b8a6d65 100644
--- a/tests/modules/services/dropbox/basic-configuration.nix
+++ b/tests/modules/services/dropbox/basic-configuration.nix
@@ -7,13 +7,7 @@
       path = "${config.home.homeDirectory}/dropbox";
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        dropbox-cli = pkgs.writeScriptBin "dummy-dropbox-cli" "" // {
-          outPath = "@dropbox-cli@";
-        };
-      })
-    ];
+    test.stubs.dropbox-cli = { };
 
     nmt.script = ''
       serviceFile=home-files/.config/systemd/user/dropbox.service
diff --git a/tests/modules/services/fluidsynth/service.nix b/tests/modules/services/fluidsynth/service.nix
index 9115eb0d..7fbfa79c 100644
--- a/tests/modules/services/fluidsynth/service.nix
+++ b/tests/modules/services/fluidsynth/service.nix
@@ -5,13 +5,7 @@
     services.fluidsynth.soundFont = "/path/to/soundFont";
     services.fluidsynth.extraOptions = [ "--sample-rate 96000" ];
 
-    nixpkgs.overlays = [
-      (self: super: {
-        fluidsynth = pkgs.writeScriptBin "dummy-fluidsynth" "" // {
-          outPath = "@fluidsynth@";
-        };
-      })
-    ];
+    test.stubs.fluidsynth = { };
 
     nmt.script = ''
       serviceFile=home-files/.config/systemd/user/fluidsynth.service
diff --git a/tests/modules/services/fnott/example-settings.nix b/tests/modules/services/fnott/example-settings.nix
index 3685637d..16b591ff 100644
--- a/tests/modules/services/fnott/example-settings.nix
+++ b/tests/modules/services/fnott/example-settings.nix
@@ -4,7 +4,7 @@
   config = {
     services.fnott = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-fnott" "";
+      package = config.lib.test.mkStubPackage { };
 
       settings = {
         main = { notification-margin = 5; };
diff --git a/tests/modules/services/fnott/global-properties.nix b/tests/modules/services/fnott/global-properties.nix
index 5a9d7e03..3be88d78 100644
--- a/tests/modules/services/fnott/global-properties.nix
+++ b/tests/modules/services/fnott/global-properties.nix
@@ -5,7 +5,7 @@
   config = {
     services.fnott = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-fnott" "";
+      package = config.lib.test.mkStubPackage { };
 
       settings = {
         main = {
diff --git a/tests/modules/services/fnott/systemd-user-service.nix b/tests/modules/services/fnott/systemd-user-service.nix
index 05859277..7efa0643 100644
--- a/tests/modules/services/fnott/systemd-user-service.nix
+++ b/tests/modules/services/fnott/systemd-user-service.nix
@@ -4,7 +4,7 @@
   config = {
     services.fnott = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-foot" "" // { outPath = "@fnott@"; };
+      package = config.lib.test.mkStubPackage { outPath = "@fnott@"; };
     };
 
     nmt.script = ''
diff --git a/tests/modules/services/git-sync/basic.nix b/tests/modules/services/git-sync/basic.nix
index 2e9ec9ad..0e9c7ad6 100644
--- a/tests/modules/services/git-sync/basic.nix
+++ b/tests/modules/services/git-sync/basic.nix
@@ -4,7 +4,7 @@
   config = {
     services.git-sync = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy" "" // { outPath = "@git-sync@"; };
+      package = config.lib.test.mkStubPackage { outPath = "@git-sync@"; };
       repositories.test = {
         path = "/a/path";
         uri = "git+ssh://user@example.com:/~user/path/to/repo.git";
diff --git a/tests/modules/services/gpg-agent/default-homedir.nix b/tests/modules/services/gpg-agent/default-homedir.nix
index f7ebf573..1b4333e1 100644
--- a/tests/modules/services/gpg-agent/default-homedir.nix
+++ b/tests/modules/services/gpg-agent/default-homedir.nix
@@ -7,8 +7,7 @@ with lib;
     services.gpg-agent.enable = true;
     programs.gpg.enable = true;
 
-    nixpkgs.overlays =
-      [ (self: super: { gnupg = pkgs.writeScriptBin "dummy-gnupg" ""; }) ];
+    test.stubs.gnupg = { };
 
     nmt.script = ''
       in="${config.systemd.user.sockets.gpg-agent.Socket.ListenStream}"
diff --git a/tests/modules/services/gpg-agent/override-homedir.nix b/tests/modules/services/gpg-agent/override-homedir.nix
index 6705a001..6c231a3b 100644
--- a/tests/modules/services/gpg-agent/override-homedir.nix
+++ b/tests/modules/services/gpg-agent/override-homedir.nix
@@ -10,8 +10,7 @@ with lib;
       homedir = "${config.home.homeDirectory}/foo/bar";
     };
 
-    nixpkgs.overlays =
-      [ (self: super: { gnupg = pkgs.writeScriptBin "dummy-gnupg" ""; }) ];
+    test.stubs.gnupg = { };
 
     nmt.script = ''
       in="${config.systemd.user.sockets.gpg-agent.Socket.ListenStream}"
diff --git a/tests/modules/services/kanshi/basic-configuration.nix b/tests/modules/services/kanshi/basic-configuration.nix
index 15fbbb9c..b8cd5d21 100644
--- a/tests/modules/services/kanshi/basic-configuration.nix
+++ b/tests/modules/services/kanshi/basic-configuration.nix
@@ -2,7 +2,7 @@
   config = {
     services.kanshi = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-kanshi" "";
+      package = config.lib.test.mkStubPackage { };
       profiles = {
         nomad = {
           outputs = [{
diff --git a/tests/modules/services/lieer/lieer-service-expected.service b/tests/modules/services/lieer/lieer-service-expected.service
index 8437b989..1d282eb9 100644
--- a/tests/modules/services/lieer/lieer-service-expected.service
+++ b/tests/modules/services/lieer/lieer-service-expected.service
@@ -1,6 +1,6 @@
 [Service]
 Environment=NOTMUCH_CONFIG=/home/hm-user/.config/notmuch/notmuchrc
-ExecStart=@lieer@/bin/gmi sync
+ExecStart=@gmailieer@/bin/gmi sync
 Type=oneshot
 WorkingDirectory=/home/hm-user/Mail/hm@example.com
 
diff --git a/tests/modules/services/lieer/lieer-service.nix b/tests/modules/services/lieer/lieer-service.nix
index af3074b0..f624ae82 100644
--- a/tests/modules/services/lieer/lieer-service.nix
+++ b/tests/modules/services/lieer/lieer-service.nix
@@ -19,13 +19,7 @@ with lib;
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        gmailieer = pkgs.writeScriptBin "dummy-gmailieer" "" // {
-          outPath = "@lieer@";
-        };
-      })
-    ];
+    test.stubs.gmailieer = { };
 
     nmt.script = ''
       assertFileExists home-files/.config/systemd/user/lieer-hm-example-com.service
diff --git a/tests/modules/services/pantalaimon/basic-configuration.nix b/tests/modules/services/pantalaimon/basic-configuration.nix
index f04101c0..ac36c0b8 100644
--- a/tests/modules/services/pantalaimon/basic-configuration.nix
+++ b/tests/modules/services/pantalaimon/basic-configuration.nix
@@ -4,9 +4,7 @@
   config = {
     services.pantalaimon = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-pantalaimon" "" // {
-        outPath = "@pantalaimon@";
-      };
+      package = config.lib.test.mkStubPackage { outPath = "@pantalaimon@"; };
       settings = {
         Default = {
           LogLevel = "Debug";
diff --git a/tests/modules/services/pbgopy/service.nix b/tests/modules/services/pbgopy/service.nix
index fb03c355..46502453 100644
--- a/tests/modules/services/pbgopy/service.nix
+++ b/tests/modules/services/pbgopy/service.nix
@@ -2,13 +2,7 @@
   config = {
     services.pbgopy.enable = true;
 
-    nixpkgs.overlays = [
-      (self: super: {
-        pbgopy = pkgs.writeScriptBin "dummy-pbgopy" "" // {
-          outPath = "@pbgopy@";
-        };
-      })
-    ];
+    test.stubs.pbgopy = { };
 
     nmt.script = ''
       serviceFile=home-files/.config/systemd/user/pbgopy.service
diff --git a/tests/modules/services/polybar/basic-configuration.nix b/tests/modules/services/polybar/basic-configuration.nix
index fd23256c..b6374acd 100644
--- a/tests/modules/services/polybar/basic-configuration.nix
+++ b/tests/modules/services/polybar/basic-configuration.nix
@@ -4,7 +4,7 @@
   config = {
     services.polybar = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-polybar" "";
+      package = config.lib.test.mkStubPackage { };
       script = "polybar bar &";
       config = {
         "bar/top" = {
diff --git a/tests/modules/services/redshift-gammastep/gammastep-basic-configuration.nix b/tests/modules/services/redshift-gammastep/gammastep-basic-configuration.nix
index 9ccf3852..6f0454bf 100644
--- a/tests/modules/services/redshift-gammastep/gammastep-basic-configuration.nix
+++ b/tests/modules/services/redshift-gammastep/gammastep-basic-configuration.nix
@@ -16,13 +16,7 @@
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        gammastep = pkgs.writeScriptBin "dummy-gammastep" "" // {
-          outPath = "@gammastep@";
-        };
-      })
-    ];
+    test.stubs.gammastep = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/services/redshift-gammastep/redshift-basic-configuration.nix b/tests/modules/services/redshift-gammastep/redshift-basic-configuration.nix
index 5e2fe40e..691d01e2 100644
--- a/tests/modules/services/redshift-gammastep/redshift-basic-configuration.nix
+++ b/tests/modules/services/redshift-gammastep/redshift-basic-configuration.nix
@@ -16,13 +16,7 @@
       };
     };
 
-    nixpkgs.overlays = [
-      (self: super: {
-        redshift = pkgs.writeScriptBin "dummy-redshift" "" // {
-          outPath = "@redshift@";
-        };
-      })
-    ];
+    test.stubs.redshift = { };
 
     nmt.script = ''
       assertFileContent \
diff --git a/tests/modules/services/sxhkd/configuration.nix b/tests/modules/services/sxhkd/configuration.nix
index e9d85477..9e996505 100644
--- a/tests/modules/services/sxhkd/configuration.nix
+++ b/tests/modules/services/sxhkd/configuration.nix
@@ -1,34 +1,32 @@
-{ config, pkgs, ... }: {
-  config = {
-    services.sxhkd = {
-      enable = true;
+{ config, pkgs, ... }:
 
-      package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out" // {
-        outPath = "@sxhkd@";
-      };
+{
+  services.sxhkd = {
+    enable = true;
 
-      keybindings = {
-        "super + a" = "run command a";
-        "super + b" = null;
-        "super + Shift + b" = "run command b";
-      };
+    package = config.lib.test.mkStubPackage { outPath = "@sxhkd@"; };
 
-      extraConfig = ''
-        super + c
-          call command c
-
-        # comment
-        super + d
-          call command d
-      '';
+    keybindings = {
+      "super + a" = "run command a";
+      "super + b" = null;
+      "super + Shift + b" = "run command b";
     };
 
-    nmt.script = ''
-      sxhkdrc=home-files/.config/sxhkd/sxhkdrc
+    extraConfig = ''
+      super + c
+        call command c
 
-      assertFileExists $sxhkdrc
-
-      assertFileContent $sxhkdrc ${./sxhkdrc}
+      # comment
+      super + d
+        call command d
     '';
   };
+
+  nmt.script = ''
+    sxhkdrc=home-files/.config/sxhkd/sxhkdrc
+
+    assertFileExists $sxhkdrc
+
+    assertFileContent $sxhkdrc ${./sxhkdrc}
+  '';
 }
diff --git a/tests/modules/services/sxhkd/service.nix b/tests/modules/services/sxhkd/service.nix
index 44bed425..84f3086a 100644
--- a/tests/modules/services/sxhkd/service.nix
+++ b/tests/modules/services/sxhkd/service.nix
@@ -1,30 +1,26 @@
 { config, pkgs, ... }:
 
 {
-  config = {
-    xsession = {
-      enable = true;
-      windowManager.command = "";
-    };
-
-    services.sxhkd = {
-      enable = true;
-      package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out" // {
-        outPath = "@sxhkd@";
-      };
-      extraOptions = [ "-m 1" ];
-    };
-
-    nmt.script = ''
-      xsessionFile=home-files/.xsession
-
-      assertFileExists $xsessionFile
-
-      assertFileContains $xsessionFile \
-        'systemctl --user stop sxhkd.scope 2> /dev/null || true'
-
-      assertFileContains $xsessionFile \
-        'systemd-cat -t sxhkd systemd-run --user --scope -u sxhkd @sxhkd@/bin/sxhkd -m 1 &'
-    '';
+  xsession = {
+    enable = true;
+    windowManager.command = "";
   };
+
+  services.sxhkd = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sxhkd@"; };
+    extraOptions = [ "-m 1" ];
+  };
+
+  nmt.script = ''
+    xsessionFile=home-files/.xsession
+
+    assertFileExists $xsessionFile
+
+    assertFileContains $xsessionFile \
+      'systemctl --user stop sxhkd.scope 2> /dev/null || true'
+
+    assertFileContains $xsessionFile \
+      'systemd-cat -t sxhkd systemd-run --user --scope -u sxhkd @sxhkd@/bin/sxhkd -m 1 &'
+  '';
 }
diff --git a/tests/modules/services/syncthing/tray-as-bool-triggers-warning.nix b/tests/modules/services/syncthing/tray-as-bool-triggers-warning.nix
index 9f9dc2ba..ca018c2d 100644
--- a/tests/modules/services/syncthing/tray-as-bool-triggers-warning.nix
+++ b/tests/modules/services/syncthing/tray-as-bool-triggers-warning.nix
@@ -6,14 +6,12 @@ with lib;
   config = {
     services.syncthing.tray = true;
 
-    nixpkgs.overlays = [
-      (self: super: { syncthingtray-minimal = pkgs.writeScriptBin "dummy" ""; })
-    ];
-
     test.asserts.warnings.expected = [
       "Specifying 'services.syncthing.tray' as a boolean is deprecated, set 'services.syncthing.tray.enable' instead. See https://github.com/nix-community/home-manager/pull/1257."
     ];
 
+    test.stubs.syncthingtray-minimal = { };
+
     nmt.script = ''
       assertFileExists home-files/.config/systemd/user/syncthingtray.service
     '';
diff --git a/tests/modules/services/trayer/basic-configuration.nix b/tests/modules/services/trayer/basic-configuration.nix
index 23632331..3020e631 100644
--- a/tests/modules/services/trayer/basic-configuration.nix
+++ b/tests/modules/services/trayer/basic-configuration.nix
@@ -4,9 +4,7 @@
   config = {
     services.trayer = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-trayer" "" // {
-        outPath = "@trayer@";
-      };
+      package = config.lib.test.mkStubPackage { outPath = "@trayer@"; };
       settings = {
         edge = "top";
         padding = 6;
diff --git a/tests/modules/services/window-managers/i3/i3-bar-focused-colors.nix b/tests/modules/services/window-managers/i3/i3-bar-focused-colors.nix
index aaa6809f..66b4ca87 100644
--- a/tests/modules/services/window-managers/i3/i3-bar-focused-colors.nix
+++ b/tests/modules/services/window-managers/i3/i3-bar-focused-colors.nix
@@ -1,25 +1,21 @@
 { config, lib, ... }:
 
-with lib;
-
 {
-  config = {
-    xsession.windowManager.i3 = {
-      enable = true;
+  imports = [ ./i3-stubs.nix ];
 
-      config.bars = [{
-        colors.focusedBackground = "#ffffff";
-        colors.focusedStatusline = "#000000";
-        colors.focusedSeparator = "#999999";
-      }];
-    };
+  xsession.windowManager.i3 = {
+    enable = true;
 
-    nixpkgs.overlays = [ (import ./i3-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/i3/config
-      assertFileContent home-files/.config/i3/config \
-        ${./i3-bar-focused-colors-expected.conf}
-    '';
+    config.bars = [{
+      colors.focusedBackground = "#ffffff";
+      colors.focusedStatusline = "#000000";
+      colors.focusedSeparator = "#999999";
+    }];
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/i3/config
+    assertFileContent home-files/.config/i3/config \
+      ${./i3-bar-focused-colors-expected.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/i3/i3-fonts-deprecated.nix b/tests/modules/services/window-managers/i3/i3-fonts-deprecated.nix
index c5142ed4..7e4532e5 100644
--- a/tests/modules/services/window-managers/i3/i3-fonts-deprecated.nix
+++ b/tests/modules/services/window-managers/i3/i3-fonts-deprecated.nix
@@ -1,29 +1,25 @@
 { config, lib, ... }:
 
-with lib;
-
 {
-  config = {
-    xsession.windowManager.i3 = {
-      enable = true;
+  imports = [ ./i3-stubs.nix ];
 
-      config = {
-        bars = [{ fonts = [ "FontAwesome" "Iosevka 11.500000" ]; }];
-        fonts = [ "DejaVuSansMono" "Terminus Bold Semi-Condensed 13.500000" ];
-      };
+  xsession.windowManager.i3 = {
+    enable = true;
+
+    config = {
+      bars = [{ fonts = [ "FontAwesome" "Iosevka 11.500000" ]; }];
+      fonts = [ "DejaVuSansMono" "Terminus Bold Semi-Condensed 13.500000" ];
     };
-
-    nixpkgs.overlays = [ (import ./i3-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/i3/config
-      assertFileContent home-files/.config/i3/config \
-        ${./i3-fonts-expected.conf}
-    '';
-
-    test.asserts.warnings.expected = [
-      "Specifying i3.config.fonts as a list is deprecated. Use the attrset version instead."
-      "Specifying i3.config.bars[].fonts as a list is deprecated. Use the attrset version instead."
-    ];
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/i3/config
+    assertFileContent home-files/.config/i3/config \
+      ${./i3-fonts-expected.conf}
+  '';
+
+  test.asserts.warnings.expected = [
+    "Specifying i3.config.fonts as a list is deprecated. Use the attrset version instead."
+    "Specifying i3.config.bars[].fonts as a list is deprecated. Use the attrset version instead."
+  ];
 }
diff --git a/tests/modules/services/window-managers/i3/i3-fonts.nix b/tests/modules/services/window-managers/i3/i3-fonts.nix
index 20ea5cab..3618451f 100644
--- a/tests/modules/services/window-managers/i3/i3-fonts.nix
+++ b/tests/modules/services/window-managers/i3/i3-fonts.nix
@@ -1,33 +1,29 @@
 { config, lib, ... }:
 
-with lib;
-
 {
-  config = {
-    xsession.windowManager.i3 = {
-      enable = true;
+  imports = [ ./i3-stubs.nix ];
 
-      config = {
-        bars = [{
-          fonts = {
-            names = [ "FontAwesome" "Iosevka" ];
-            size = 11.5;
-          };
-        }];
+  xsession.windowManager.i3 = {
+    enable = true;
+
+    config = {
+      bars = [{
         fonts = {
-          names = [ "DejaVuSansMono" "Terminus" ];
-          style = "Bold Semi-Condensed";
-          size = 13.5;
+          names = [ "FontAwesome" "Iosevka" ];
+          size = 11.5;
         };
+      }];
+      fonts = {
+        names = [ "DejaVuSansMono" "Terminus" ];
+        style = "Bold Semi-Condensed";
+        size = 13.5;
       };
     };
-
-    nixpkgs.overlays = [ (import ./i3-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/i3/config
-      assertFileContent home-files/.config/i3/config \
-        ${./i3-fonts-expected.conf}
-    '';
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/i3/config
+    assertFileContent home-files/.config/i3/config \
+      ${./i3-fonts-expected.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/i3/i3-keybindings.nix b/tests/modules/services/window-managers/i3/i3-keybindings.nix
index bc3cae6e..2137c53e 100644
--- a/tests/modules/services/window-managers/i3/i3-keybindings.nix
+++ b/tests/modules/services/window-managers/i3/i3-keybindings.nix
@@ -1,27 +1,23 @@
 { config, lib, ... }:
 
-with lib;
-
 {
-  config = {
-    xsession.windowManager.i3 = {
-      enable = true;
+  imports = [ ./i3-stubs.nix ];
 
-      config.keybindings =
-        let modifier = config.xsession.windowManager.i3.config.modifier;
-        in lib.mkOptionDefault {
-          "${modifier}+Left" = "overridden-command";
-          "${modifier}+Right" = null;
-          "${modifier}+Invented" = "invented-key-command";
-        };
-    };
+  xsession.windowManager.i3 = {
+    enable = true;
 
-    nixpkgs.overlays = [ (import ./i3-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/i3/config
-      assertFileContent home-files/.config/i3/config \
-        ${./i3-keybindings-expected.conf}
-    '';
+    config.keybindings =
+      let modifier = config.xsession.windowManager.i3.config.modifier;
+      in lib.mkOptionDefault {
+        "${modifier}+Left" = "overridden-command";
+        "${modifier}+Right" = null;
+        "${modifier}+Invented" = "invented-key-command";
+      };
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/i3/config
+    assertFileContent home-files/.config/i3/config \
+      ${./i3-keybindings-expected.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/i3/i3-null-config.nix b/tests/modules/services/window-managers/i3/i3-null-config.nix
index a9b37882..1c221319 100644
--- a/tests/modules/services/window-managers/i3/i3-null-config.nix
+++ b/tests/modules/services/window-managers/i3/i3-null-config.nix
@@ -1,20 +1,16 @@
 { config, lib, pkgs, ... }:
 
-with lib;
-
 {
-  config = {
-    xsession.windowManager.i3 = {
-      enable = true;
-      config = null;
-    };
+  imports = [ ./i3-stubs.nix ];
 
-    nixpkgs.overlays = [ (import ./i3-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/i3/config
-      assertFileContent home-files/.config/i3/config \
-        ${pkgs.writeText "expected" "\n"}
-    '';
+  xsession.windowManager.i3 = {
+    enable = true;
+    config = null;
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/i3/config
+    assertFileContent home-files/.config/i3/config \
+      ${pkgs.writeText "expected" "\n"}
+  '';
 }
diff --git a/tests/modules/services/window-managers/i3/i3-overlay.nix b/tests/modules/services/window-managers/i3/i3-overlay.nix
deleted file mode 100644
index fead262f..00000000
--- a/tests/modules/services/window-managers/i3/i3-overlay.nix
+++ /dev/null
@@ -1,12 +0,0 @@
-self: super:
-# Avoid unnecessary downloads in CI jobs and/or make out paths
-# constant, i.e., not containing hashes, version numbers etc.
-{
-  dmenu = super.dmenu // { outPath = "@dmenu@"; };
-
-  i3 = super.writeScriptBin "i3" "" // { outPath = "@i3@"; };
-
-  i3-gaps = super.writeScriptBin "i3" "" // { outPath = "@i3-gaps@"; };
-
-  i3status = super.i3status // { outPath = "@i3status@"; };
-}
diff --git a/tests/modules/services/window-managers/i3/i3-stubs.nix b/tests/modules/services/window-managers/i3/i3-stubs.nix
new file mode 100644
index 00000000..cfb892ac
--- /dev/null
+++ b/tests/modules/services/window-managers/i3/i3-stubs.nix
@@ -0,0 +1,19 @@
+{
+  # Avoid unnecessary downloads in CI jobs and/or make out paths constant, i.e.,
+  # not containing hashes, version numbers etc.
+  test.stubs = {
+    dmenu = { };
+
+    i3 = {
+      buildScript = ''
+        mkdir -p $out/bin
+        echo '#!/bin/sh' > $out/bin/i3
+        chmod 755 $out/bin/i3
+      '';
+    };
+
+    i3-gaps = { };
+
+    i3status = { };
+  };
+}
diff --git a/tests/modules/services/window-managers/i3/i3-workspace-default.nix b/tests/modules/services/window-managers/i3/i3-workspace-default.nix
index 0a825b1e..521b5f5d 100644
--- a/tests/modules/services/window-managers/i3/i3-workspace-default.nix
+++ b/tests/modules/services/window-managers/i3/i3-workspace-default.nix
@@ -1,21 +1,17 @@
 { config, lib, ... }:
 
-with lib;
-
 {
-  config = {
-    xsession.windowManager.i3 = {
-      enable = true;
+  imports = [ ./i3-stubs.nix ];
 
-      config.defaultWorkspace = "workspace number 1";
-    };
+  xsession.windowManager.i3 = {
+    enable = true;
 
-    nixpkgs.overlays = [ (import ./i3-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/i3/config
-      assertFileContent home-files/.config/i3/config \
-        ${./i3-workspace-default-expected.conf}
-    '';
+    config.defaultWorkspace = "workspace number 1";
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/i3/config
+    assertFileContent home-files/.config/i3/config \
+      ${./i3-workspace-default-expected.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/i3/i3-workspace-output.nix b/tests/modules/services/window-managers/i3/i3-workspace-output.nix
index b2ff90e0..df4a2c78 100644
--- a/tests/modules/services/window-managers/i3/i3-workspace-output.nix
+++ b/tests/modules/services/window-managers/i3/i3-workspace-output.nix
@@ -1,46 +1,42 @@
 { config, lib, ... }:
 
-with lib;
-
-{
-  config = let
-    i3 = {
-      ws1 = "1";
-      ws2 = "ABC";
-      ws3 = "3: Test";
-      ws4 = ''!"§$%&/(){}[]=?\*#<>-_.:,;²³'';
-    };
-
-  in {
-    xsession.windowManager.i3 = {
-      enable = true;
-
-      config.workspaceOutputAssign = [
-        {
-          workspace = "${i3.ws1}";
-          output = "eDP";
-        }
-        {
-          workspace = "${i3.ws2}";
-          output = "DP";
-        }
-        {
-          workspace = "${i3.ws3}";
-          output = "HDMI";
-        }
-        {
-          workspace = "${i3.ws4}";
-          output = "DVI";
-        }
-      ];
-    };
-
-    nixpkgs.overlays = [ (import ./i3-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/i3/config
-      assertFileContent home-files/.config/i3/config \
-        ${./i3-workspace-output-expected.conf}
-    '';
+let
+  i3 = {
+    ws1 = "1";
+    ws2 = "ABC";
+    ws3 = "3: Test";
+    ws4 = ''!"§$%&/(){}[]=?\*#<>-_.:,;²³'';
   };
+
+in {
+  imports = [ ./i3-stubs.nix ];
+
+  xsession.windowManager.i3 = {
+    enable = true;
+
+    config.workspaceOutputAssign = [
+      {
+        workspace = "${i3.ws1}";
+        output = "eDP";
+      }
+      {
+        workspace = "${i3.ws2}";
+        output = "DP";
+      }
+      {
+        workspace = "${i3.ws3}";
+        output = "HDMI";
+      }
+      {
+        workspace = "${i3.ws4}";
+        output = "DVI";
+      }
+    ];
+  };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/i3/config
+    assertFileContent home-files/.config/i3/config \
+      ${./i3-workspace-output-expected.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-bar-focused-colors.conf b/tests/modules/services/window-managers/sway/sway-bar-focused-colors.conf
index dc8319d6..558e579a 100644
--- a/tests/modules/services/window-managers/sway/sway-bar-focused-colors.conf
+++ b/tests/modules/services/window-managers/sway/sway-bar-focused-colors.conf
@@ -90,7 +90,7 @@ bar {
   hidden_state hide
   position bottom
   status_command @i3status@/bin/i3status
-  swaybar_command @sway/bin/swaybar
+  swaybar_command @sway@/bin/swaybar
   workspace_buttons yes
   strip_workspace_numbers no
   tray_output primary
diff --git a/tests/modules/services/window-managers/sway/sway-bar-focused-colors.nix b/tests/modules/services/window-managers/sway/sway-bar-focused-colors.nix
index 8b3df36e..9746d050 100644
--- a/tests/modules/services/window-managers/sway/sway-bar-focused-colors.nix
+++ b/tests/modules/services/window-managers/sway/sway-bar-focused-colors.nix
@@ -1,32 +1,24 @@
 { config, lib, pkgs, ... }:
 
-with lib;
+{
+  imports = [ ./sway-stubs.nix ];
 
-let
+  wayland.windowManager.sway = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sway@"; };
+    # overriding findutils causes issues
+    config.menu = "${pkgs.dmenu}/bin/dmenu_run";
 
-  dummy-package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out";
-
-in {
-  config = {
-    wayland.windowManager.sway = {
-      enable = true;
-      package = dummy-package // { outPath = "@sway"; };
-      # overriding findutils causes issues
-      config.menu = "${pkgs.dmenu}/bin/dmenu_run";
-
-      config.bars = [{
-        colors.focusedBackground = "#ffffff";
-        colors.focusedStatusline = "#000000";
-        colors.focusedSeparator = "#999999";
-      }];
-    };
-
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${./sway-bar-focused-colors.conf}
-    '';
+    config.bars = [{
+      colors.focusedBackground = "#ffffff";
+      colors.focusedStatusline = "#000000";
+      colors.focusedSeparator = "#999999";
+    }];
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${./sway-bar-focused-colors.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-bindkeys-to-code.conf b/tests/modules/services/window-managers/sway/sway-bindkeys-to-code.conf
index 609b0b02..7879ceab 100644
--- a/tests/modules/services/window-managers/sway/sway-bindkeys-to-code.conf
+++ b/tests/modules/services/window-managers/sway/sway-bindkeys-to-code.conf
@@ -90,7 +90,7 @@ bar {
   hidden_state hide
   position bottom
   status_command @i3status@/bin/i3status
-  swaybar_command @sway/bin/swaybar
+  swaybar_command @sway@/bin/swaybar
   workspace_buttons yes
   strip_workspace_numbers no
   tray_output primary
diff --git a/tests/modules/services/window-managers/sway/sway-bindkeys-to-code.nix b/tests/modules/services/window-managers/sway/sway-bindkeys-to-code.nix
index bdcc4dc1..5e62748c 100644
--- a/tests/modules/services/window-managers/sway/sway-bindkeys-to-code.nix
+++ b/tests/modules/services/window-managers/sway/sway-bindkeys-to-code.nix
@@ -1,27 +1,19 @@
 { config, lib, pkgs, ... }:
 
-with lib;
+{
+  imports = [ ./sway-stubs.nix ];
 
-let
-
-  dummy-package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out";
-
-in {
-  config = {
-    wayland.windowManager.sway = {
-      enable = true;
-      package = dummy-package // { outPath = "@sway"; };
-      # overriding findutils causes issues
-      config.menu = "${pkgs.dmenu}/bin/dmenu_run";
-      config.bindkeysToCode = true;
-    };
-
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${./sway-bindkeys-to-code.conf}
-    '';
+  wayland.windowManager.sway = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sway@"; };
+    # overriding findutils causes issues
+    config.menu = "${pkgs.dmenu}/bin/dmenu_run";
+    config.bindkeysToCode = true;
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${./sway-bindkeys-to-code.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-default.conf b/tests/modules/services/window-managers/sway/sway-default.conf
index cbcd2d83..1cd75fd5 100644
--- a/tests/modules/services/window-managers/sway/sway-default.conf
+++ b/tests/modules/services/window-managers/sway/sway-default.conf
@@ -90,7 +90,7 @@ bar {
   hidden_state hide
   position bottom
   status_command @i3status@/bin/i3status
-  swaybar_command @sway/bin/swaybar
+  swaybar_command @sway@/bin/swaybar
   workspace_buttons yes
   strip_workspace_numbers no
   tray_output primary
diff --git a/tests/modules/services/window-managers/sway/sway-default.nix b/tests/modules/services/window-managers/sway/sway-default.nix
index 141f6303..7bd43731 100644
--- a/tests/modules/services/window-managers/sway/sway-default.nix
+++ b/tests/modules/services/window-managers/sway/sway-default.nix
@@ -1,26 +1,18 @@
 { config, lib, pkgs, ... }:
 
-with lib;
+{
+  imports = [ ./sway-stubs.nix ];
 
-let
-
-  dummy-package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out";
-
-in {
-  config = {
-    wayland.windowManager.sway = {
-      enable = true;
-      package = dummy-package // { outPath = "@sway"; };
-      # overriding findutils causes issues
-      config.menu = "${pkgs.dmenu}/bin/dmenu_run";
-    };
-
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${./sway-default.conf}
-    '';
+  wayland.windowManager.sway = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sway@"; };
+    # overriding findutils causes issues
+    config.menu = "${pkgs.dmenu}/bin/dmenu_run";
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${./sway-default.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-followmouse-legacy.nix b/tests/modules/services/window-managers/sway/sway-followmouse-legacy.nix
index b83c8d1b..ce69d9f7 100644
--- a/tests/modules/services/window-managers/sway/sway-followmouse-legacy.nix
+++ b/tests/modules/services/window-managers/sway/sway-followmouse-legacy.nix
@@ -2,29 +2,23 @@
 
 with lib;
 
-let
+{
+  imports = [ ./sway-stubs.nix ];
 
-  dummy-package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out";
+  wayland.windowManager.sway = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sway@"; };
 
-in {
-  config = {
-    wayland.windowManager.sway = {
-      enable = true;
-      package = dummy-package // { outPath = "@sway"; };
-
-      config = {
-        focus.followMouse = false;
-        menu = "${pkgs.dmenu}/bin/dmenu_run";
-        bars = [ ];
-      };
+    config = {
+      focus.followMouse = false;
+      menu = "${pkgs.dmenu}/bin/dmenu_run";
+      bars = [ ];
     };
-
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${./sway-followmouse-legacy-expected.conf}
-    '';
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${./sway-followmouse-legacy-expected.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-followmouse.nix b/tests/modules/services/window-managers/sway/sway-followmouse.nix
index 9d18b691..7065dd1c 100644
--- a/tests/modules/services/window-managers/sway/sway-followmouse.nix
+++ b/tests/modules/services/window-managers/sway/sway-followmouse.nix
@@ -1,30 +1,22 @@
 { config, lib, pkgs, ... }:
 
-with lib;
+{
+  imports = [ ./sway-stubs.nix ];
 
-let
+  wayland.windowManager.sway = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sway@"; };
 
-  dummy-package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out";
-
-in {
-  config = {
-    wayland.windowManager.sway = {
-      enable = true;
-      package = dummy-package // { outPath = "@sway"; };
-
-      config = {
-        focus.followMouse = "always";
-        menu = "${pkgs.dmenu}/bin/dmenu_run";
-        bars = [ ];
-      };
+    config = {
+      focus.followMouse = "always";
+      menu = "${pkgs.dmenu}/bin/dmenu_run";
+      bars = [ ];
     };
-
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${./sway-followmouse-expected.conf}
-    '';
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${./sway-followmouse-expected.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-modules.conf b/tests/modules/services/window-managers/sway/sway-modules.conf
index ee633305..1cec60e8 100644
--- a/tests/modules/services/window-managers/sway/sway-modules.conf
+++ b/tests/modules/services/window-managers/sway/sway-modules.conf
@@ -102,7 +102,7 @@ bar {
   hidden_state hide
   position bottom
   status_command @i3status@/bin/i3status
-  swaybar_command @sway/bin/swaybar
+  swaybar_command @sway@/bin/swaybar
   workspace_buttons yes
   strip_workspace_numbers no
   tray_output primary
diff --git a/tests/modules/services/window-managers/sway/sway-modules.nix b/tests/modules/services/window-managers/sway/sway-modules.nix
index fbe927f3..96366ab0 100644
--- a/tests/modules/services/window-managers/sway/sway-modules.nix
+++ b/tests/modules/services/window-managers/sway/sway-modules.nix
@@ -1,32 +1,24 @@
 { config, lib, pkgs, ... }:
 
-with lib;
+{
+  imports = [ ./sway-stubs.nix ];
 
-let
+  wayland.windowManager.sway = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sway@"; };
+    # overriding findutils causes issues
+    config = {
+      menu = "${pkgs.dmenu}/bin/dmenu_run";
 
-  dummy-package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out";
-
-in {
-  config = {
-    wayland.windowManager.sway = {
-      enable = true;
-      package = dummy-package // { outPath = "@sway"; };
-      # overriding findutils causes issues
-      config = {
-        menu = "${pkgs.dmenu}/bin/dmenu_run";
-
-        input = { "*" = { xkb_variant = "dvorak"; }; };
-        output = { "HDMI-A-2" = { bg = "~/path/to/background.png fill"; }; };
-        seat = { "*" = { hide_cursor = "when-typing enable"; }; };
-      };
+      input = { "*" = { xkb_variant = "dvorak"; }; };
+      output = { "HDMI-A-2" = { bg = "~/path/to/background.png fill"; }; };
+      seat = { "*" = { hide_cursor = "when-typing enable"; }; };
     };
-
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${./sway-modules.conf}
-    '';
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${./sway-modules.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-null-config.nix b/tests/modules/services/window-managers/sway/sway-null-config.nix
index fc01660c..4033903d 100644
--- a/tests/modules/services/window-managers/sway/sway-null-config.nix
+++ b/tests/modules/services/window-managers/sway/sway-null-config.nix
@@ -1,22 +1,18 @@
 { config, lib, pkgs, ... }:
 
-with lib;
-
 {
-  config = {
-    wayland.windowManager.sway = {
-      enable = true;
-      config = null;
-      systemdIntegration = false;
-      package = pkgs.sway;
-    };
+  imports = [ ./sway-stubs.nix ];
 
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${pkgs.writeText "expected" "\n"}
-    '';
+  wayland.windowManager.sway = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sway@"; };
+    config = null;
+    systemdIntegration = false;
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${pkgs.writeText "expected" "\n"}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-null-package.nix b/tests/modules/services/window-managers/sway/sway-null-package.nix
index 3993d638..fe2a4519 100644
--- a/tests/modules/services/window-managers/sway/sway-null-package.nix
+++ b/tests/modules/services/window-managers/sway/sway-null-package.nix
@@ -1,35 +1,27 @@
 { config, lib, pkgs, ... }:
 
-with lib;
+{
+  imports = [ ./sway-stubs.nix ];
 
-let
+  # Enables the default bar configuration
+  home.stateVersion = "20.09";
 
-  dummy-package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out";
-
-in {
-  config = {
-    # Enables the default bar configuration
-    home.stateVersion = "20.09";
-
-    wayland.windowManager.sway = {
-      enable = true;
-      package = null;
-      config.menu = "${pkgs.dmenu}/bin/dmenu_run";
-    };
-
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    assertions = [{
-      assertion =
-        !elem config.wayland.windowManager.sway.config.bars [ [ { } ] [ ] ];
-      message =
-        "The default Sway bars configuration should be set for this test (sway-null-package) to work.";
-    }];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${./sway-null-package.conf}
-    '';
+  wayland.windowManager.sway = {
+    enable = true;
+    package = null;
+    config.menu = "${pkgs.dmenu}/bin/dmenu_run";
   };
+
+  assertions = [{
+    assertion =
+      !lib.elem config.wayland.windowManager.sway.config.bars [ [ { } ] [ ] ];
+    message =
+      "The default Sway bars configuration should be set for this test (sway-null-package) to work.";
+  }];
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${./sway-null-package.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-overlay.nix b/tests/modules/services/window-managers/sway/sway-overlay.nix
deleted file mode 100644
index 4edfb205..00000000
--- a/tests/modules/services/window-managers/sway/sway-overlay.nix
+++ /dev/null
@@ -1,17 +0,0 @@
-self: super:
-# Avoid unnecessary downloads in CI jobs.
-let dummy-package = super.runCommandLocal "dummy-package" { } "mkdir $out";
-in {
-  dmenu = dummy-package // { outPath = "@dmenu@"; };
-  rxvt-unicode-unwrapped = dummy-package // {
-    outPath = "@rxvt-unicode-unwrapped@";
-  };
-  i3status = dummy-package // { outPath = "@i3status@"; };
-  sway = dummy-package // { outPath = "@sway@"; };
-  sway-unwrapped = dummy-package // {
-    outPath = "@sway-unwrapped@";
-    version = "1";
-  };
-  swaybg = dummy-package // { outPath = "@swaybg@"; };
-  xwayland = dummy-package // { outPath = "@xwayland@"; };
-}
diff --git a/tests/modules/services/window-managers/sway/sway-post-2003.nix b/tests/modules/services/window-managers/sway/sway-post-2003.nix
index ddcf2b23..7596250e 100644
--- a/tests/modules/services/window-managers/sway/sway-post-2003.nix
+++ b/tests/modules/services/window-managers/sway/sway-post-2003.nix
@@ -1,28 +1,20 @@
 { config, lib, pkgs, ... }:
 
-with lib;
+{
+  imports = [ ./sway-stubs.nix ];
 
-let
+  home.stateVersion = "20.09";
 
-  dummy-package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out";
-
-in {
-  config = {
-    home.stateVersion = "20.09";
-
-    wayland.windowManager.sway = {
-      enable = true;
-      package = dummy-package // { outPath = "@sway"; };
-      # overriding findutils causes issues
-      config.menu = "${pkgs.dmenu}/bin/dmenu_run";
-    };
-
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${./sway-default.conf}
-    '';
+  wayland.windowManager.sway = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sway@"; };
+    # overriding findutils causes issues
+    config.menu = "${pkgs.dmenu}/bin/dmenu_run";
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${./sway-default.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-stubs.nix b/tests/modules/services/window-managers/sway/sway-stubs.nix
new file mode 100644
index 00000000..55a74e1c
--- /dev/null
+++ b/tests/modules/services/window-managers/sway/sway-stubs.nix
@@ -0,0 +1,13 @@
+{
+  # Avoid unnecessary downloads in CI jobs and/or make out paths constant, i.e.,
+  # not containing hashes, version numbers etc.
+  test.stubs = {
+    dmenu = { };
+    rxvt-unicode-unwrapped = { };
+    i3status = { };
+    sway = { };
+    sway-unwrapped = { version = "1"; };
+    swaybg = { };
+    xwayland = { };
+  };
+}
diff --git a/tests/modules/services/window-managers/sway/sway-workspace-default-expected.conf b/tests/modules/services/window-managers/sway/sway-workspace-default-expected.conf
index 9441bf5c..7aa1e1e4 100644
--- a/tests/modules/services/window-managers/sway/sway-workspace-default-expected.conf
+++ b/tests/modules/services/window-managers/sway/sway-workspace-default-expected.conf
@@ -89,7 +89,7 @@ bar {
   hidden_state hide
   position bottom
   status_command @i3status@/bin/i3status
-  swaybar_command @sway/bin/swaybar
+  swaybar_command @sway@/bin/swaybar
   workspace_buttons yes
   strip_workspace_numbers no
   tray_output primary
diff --git a/tests/modules/services/window-managers/sway/sway-workspace-default.nix b/tests/modules/services/window-managers/sway/sway-workspace-default.nix
index 52f4f3ec..d9411098 100644
--- a/tests/modules/services/window-managers/sway/sway-workspace-default.nix
+++ b/tests/modules/services/window-managers/sway/sway-workspace-default.nix
@@ -1,27 +1,19 @@
 { config, lib, pkgs, ... }:
 
-with lib;
+{
+  imports = [ ./sway-stubs.nix ];
 
-let
-
-  dummy-package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out";
-
-in {
-  config = {
-    wayland.windowManager.sway = {
-      enable = true;
-      package = dummy-package // { outPath = "@sway"; };
-      # overriding findutils causes issues
-      config.menu = "${pkgs.dmenu}/bin/dmenu_run";
-      config.defaultWorkspace = "workspace number 9";
-    };
-
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${./sway-workspace-default-expected.conf}
-    '';
+  wayland.windowManager.sway = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sway@"; };
+    # overriding findutils causes issues
+    config.menu = "${pkgs.dmenu}/bin/dmenu_run";
+    config.defaultWorkspace = "workspace number 9";
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${./sway-workspace-default-expected.conf}
+  '';
 }
diff --git a/tests/modules/services/window-managers/sway/sway-workspace-output-expected.conf b/tests/modules/services/window-managers/sway/sway-workspace-output-expected.conf
index 6ef9f6d1..e4a4f6cf 100644
--- a/tests/modules/services/window-managers/sway/sway-workspace-output-expected.conf
+++ b/tests/modules/services/window-managers/sway/sway-workspace-output-expected.conf
@@ -90,7 +90,7 @@ bar {
   hidden_state hide
   position bottom
   status_command @i3status@/bin/i3status
-  swaybar_command @sway/bin/swaybar
+  swaybar_command @sway@/bin/swaybar
   workspace_buttons yes
   strip_workspace_numbers no
   tray_output primary
diff --git a/tests/modules/services/window-managers/sway/sway-workspace-output.nix b/tests/modules/services/window-managers/sway/sway-workspace-output.nix
index 5791a3da..ce51c1f5 100644
--- a/tests/modules/services/window-managers/sway/sway-workspace-output.nix
+++ b/tests/modules/services/window-managers/sway/sway-workspace-output.nix
@@ -1,53 +1,45 @@
 { config, lib, pkgs, ... }:
 
-with lib;
-
 let
-
-  dummy-package = pkgs.runCommandLocal "dummy-package" { } "mkdir $out";
+  i3 = {
+    ws1 = "1";
+    ws2 = "ABC";
+    ws3 = "3: Test";
+    ws4 = ''!"§$%&/(){}[]=?\*#<>-_.:,;²³'';
+  };
 
 in {
-  config = let
-    i3 = {
-      ws1 = "1";
-      ws2 = "ABC";
-      ws3 = "3: Test";
-      ws4 = ''!"§$%&/(){}[]=?\*#<>-_.:,;²³'';
-    };
+  imports = [ ./sway-stubs.nix ];
 
-  in {
-    wayland.windowManager.sway = {
-      enable = true;
-      package = dummy-package // { outPath = "@sway"; };
-      # overriding findutils causes issues
-      config.menu = "${pkgs.dmenu}/bin/dmenu_run";
+  wayland.windowManager.sway = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { outPath = "@sway@"; };
+    # overriding findutils causes issues
+    config.menu = "${pkgs.dmenu}/bin/dmenu_run";
 
-      config.workspaceOutputAssign = [
-        {
-          workspace = "${i3.ws1}";
-          output = "eDP";
-        }
-        {
-          workspace = "${i3.ws2}";
-          output = "DP";
-        }
-        {
-          workspace = "${i3.ws3}";
-          output = "HDMI";
-        }
-        {
-          workspace = "${i3.ws4}";
-          output = "DVI";
-        }
-      ];
-    };
-
-    nixpkgs.overlays = [ (import ./sway-overlay.nix) ];
-
-    nmt.script = ''
-      assertFileExists home-files/.config/sway/config
-      assertFileContent home-files/.config/sway/config \
-        ${./sway-workspace-output-expected.conf}
-    '';
+    config.workspaceOutputAssign = [
+      {
+        workspace = "${i3.ws1}";
+        output = "eDP";
+      }
+      {
+        workspace = "${i3.ws2}";
+        output = "DP";
+      }
+      {
+        workspace = "${i3.ws3}";
+        output = "HDMI";
+      }
+      {
+        workspace = "${i3.ws4}";
+        output = "DVI";
+      }
+    ];
   };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/sway/config
+    assertFileContent home-files/.config/sway/config \
+      ${./sway-workspace-output-expected.conf}
+  '';
 }
diff --git a/tests/modules/services/wlsunset/wlsunset-service.nix b/tests/modules/services/wlsunset/wlsunset-service.nix
index de32a827..e3f81650 100644
--- a/tests/modules/services/wlsunset/wlsunset-service.nix
+++ b/tests/modules/services/wlsunset/wlsunset-service.nix
@@ -4,9 +4,7 @@
   config = {
     services.wlsunset = {
       enable = true;
-      package = pkgs.writeScriptBin "dummy-wlsunset" "" // {
-        outPath = "@wlsunset@";
-      };
+      package = config.lib.test.mkStubPackage { outPath = "@wlsunset@"; };
       latitude = "12.3";
       longitude = "128.8";
       temperature.day = 6000;
diff --git a/tests/stubs.nix b/tests/stubs.nix
new file mode 100644
index 00000000..01f46065
--- /dev/null
+++ b/tests/stubs.nix
@@ -0,0 +1,61 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  stubType = types.submodule ({ name, ... }: {
+    options = {
+      name = mkOption {
+        type = types.str;
+        default = "dummy";
+        description = "The stub package name.";
+      };
+
+      outPath = mkOption {
+        type = types.nullOr types.str;
+        default = "@${name}@";
+        defaultText = "@\${name}@";
+      };
+
+      version = mkOption {
+        type = types.nullOr types.str;
+        default = null;
+      };
+
+      buildScript = mkOption {
+        type = types.str;
+        default = defaultBuildScript;
+      };
+    };
+  });
+
+  defaultBuildScript = "mkdir $out";
+
+  dummyPackage = pkgs.runCommandLocal "dummy" { } defaultBuildScript;
+
+  mkStubPackage = { name ? "dummy", outPath ? null, version ? null
+    , buildScript ? defaultBuildScript }:
+    let
+      pkg = if name == "dummy" && buildScript == defaultBuildScript then
+        dummyPackage
+      else
+        pkgs.runCommandLocal name { } buildScript;
+    in pkg // optionalAttrs (outPath != null) { inherit outPath; }
+    // optionalAttrs (version != null) { inherit version; };
+
+in {
+  options.test.stubs = mkOption {
+    type = types.attrsOf stubType;
+    default = { };
+    description =
+      "Package attributes that should be replaced by a stub package.";
+  };
+
+  config = {
+    lib.test.mkStubPackage = mkStubPackage;
+
+    nixpkgs.overlays = mkIf (config.test.stubs != { })
+      [ (self: super: mapAttrs (n: mkStubPackage) config.test.stubs) ];
+  };
+}