lib: add naive get XDG autostart file function

lib/xdg.nix

@@ -28,4 +28,32 @@ rec {
   */
   getXdgDesktop = drv: name:
     "${drv}/share/applications/${name}.desktop";
+
+  /**
+    Naively get the absolute path of an autostart file given a derivation and a
+    name.
+
+    # Arguments
+
+    drv
+    : The derivation.
+
+    name
+    : The name of the `.desktop` file (without the `.desktop` extension).
+
+    # Type
+
+    ```
+    getXdgDesktop :: Derivation -> String -> Path
+    ```
+
+    # Example
+
+    ```nix
+    getXdgDesktop pkgs.wezterm "org.wezfurlong.wezterm"
+    => /nix/store/$HASH-wezterm-org.wezterm.wezterm.desktop
+    ```
+  */
+  getXdgAutostartFile = drv: name:
+    "${drv}/etc/xdg/autostart/${name}.desktop";
 }

tests/lib/xdg.nix

@@ -11,4 +11,15 @@ lib.runTests {
     expr = self.xdg.getXdgDesktop pkgs.hello "non-existing-desktop";
     expected = "${pkgs.hello}/share/applications/non-existing-desktop.desktop";
   };
+
+  testGetXdgAutostartFile = {
+    expr = self.xdg.getXdgAutostartFile pkgs.valent "valent";
+    expected = "${pkgs.valent}/etc/xdg/autostart/valent.desktop";
+  };
+
+  # This should be a naive function so it should just naively get things.
+  testGetXdgAutostartFile2 = {
+    expr = self.xdg.getXdgAutostartFile pkgs.hello "non-existing-autostart";
+    expected = "${pkgs.hello}/etc/xdg/autostart/non-existing-autostart.desktop";
+  };
 }