Issue #27312: mock out function that fails when called from setupApp during

IDLE test_macosx and see if addOpenEventSupport() fails.

Lib/idlelib/idle_test/test_macosx.py

@@ -83,6 +83,7 @@ class SetupTest(unittest.TestCase):
         cls.root.destroy()
         del cls.root
 
+    @mock.patch('idlelib.macosx.overrideRootMenu')  #27312
     def test_setupapp(self):
         "Call setupApp with each possible graphics type."
         root = self.root