Allow for some branches we can't test.

android/src/toga_android/app.py

@@ -93,9 +93,10 @@ def onOptionsItemSelected(self, menuitem):
 
     def onPrepareOptionsMenu(self, menu):
         # If the main window doesn't have a toolbar, there's no preparation required;
-        # this is a simple main window, which can't have commands.
+        # this is a simple main window, which can't have commands. This can't be
+        # validated in the testbed, so it's marked no-cover.
         if not hasattr(self._impl.interface.main_window, "toolbar"):
-            return False
+            return False  # pragma: no cover
 
         menu.clear()
         itemid = 1  # 0 is the same as Menu.NONE.

android/src/toga_android/window.py

@@ -56,8 +56,9 @@ def close(self):  # pragma: no cover
         # closed, so the platform-specific close handling is never triggered.
         pass
 
-    def configure_titlebar(self):
-        # Hide the titlebar on a simple window.
+    def configure_titlebar(self):  # pragma: no cover
+        # Hide the titlebar on a simple window. The testbed can't create a simple
+        # window, so we can't test this.
         self.app.native.getSupportActionBar().hide()
 
     def set_app(self, app):

docs/reference/api/app.rst

@@ -111,6 +111,10 @@ otherwise, you wouldn't be able to exit the app.
 Notes
 -----
 
+* On macOS, menus are tied to the app, not the window; and a menu is mandatory.
+  Therefore, a minimal macOS app (i.e., an app using a :any:`toga.Window` as the main
+  window) will still have a menu, but it will only have the bare minimum of menu items.
+
 * Apps executed under Wayland on Linux environment may not show the app's formal name
   correctly. Wayland considers many aspects of app operation to be the domain of the
   windowing environment, not the app; as a result, some API requests will be ignored

iOS/src/toga_iOS/container.py

@@ -149,16 +149,17 @@ def __init__(
         # Set the controller's view to be the root content widget
         self.controller.view = self.native
 
+    # The testbed app won't instantiate a simple app, so we can't test these properties
     @property
-    def height(self):
+    def height(self):  # pragma: no cover
         return self.layout_native.bounds.size.height - self.top_offset
 
     @property
-    def top_offset(self):
+    def top_offset(self):  # pragma: no cover
         return UIApplication.sharedApplication.statusBarFrame.size.height
 
     @property
-    def title(self):
+    def title(self):  # pragma: no cover
         return self._title
 
     @title.setter