rofi: add test to verify assertion

tests/default.nix

@@ -36,6 +36,7 @@ import nmt {
     // import ./modules/misc/pam
     // import ./modules/misc/xsession
     // import ./modules/programs/firefox
+    // import ./modules/programs/rofi
     // import ./modules/systemd
   )
   // import ./modules/home-environment

tests/modules/programs/rofi/assert-on-both-theme-and-colors-expected.json

@@ -0,0 +1 @@
+["Cannot use the rofi options 'theme' and 'colors' simultaneously.\n"]

tests/modules/programs/rofi/assert-on-both-theme-and-colors.nix

@@ -0,0 +1,33 @@
+{ config, lib, ... }:
+
+with lib;
+
+{
+  config = {
+    programs.rofi = {
+      enable = true;
+      theme = "foo";
+      colors = {
+        window = {
+          background = "background";
+          border = "border";
+          separator = "separator";
+        };
+        rows = {
+        };
+      };
+    };
+
+    home.file.result.text =
+      builtins.toJSON
+      (map (a: a.message)
+      (filter (a: !a.assertion)
+        config.assertions));
+
+    nmt.script = ''
+      assertFileContent \
+        home-files/result \
+        ${./assert-on-both-theme-and-colors-expected.json}
+    '';
+  };
+}

tests/modules/programs/rofi/default.nix

@@ -0,0 +1,3 @@
+{
+  rofi-assert-on-both-theme-and-colors = import ./assert-on-both-theme-and-colors.nix;
+}