Issue #18441: add Mac (darwin) gui check. This is not needed today, but has been

in the past and might be needed again in the future

Lib/test/test_idle.py

-# Skip test if _thread or _tkinter wasn't built or idlelib was deleted.
+import unittest
 from test import test_support as support
 from test.test_support import import_module, use_resources
+
+# Skip test if _thread or _tkinter wasn't built or idlelib was deleted.
 import_module('threading')  # imported by idlelib.PyShell, imports _thread
-tk = import_module('Tkinter')
+tk = import_module('Tkinter')  # imports _tkinter
 idletest = import_module('idlelib.idle_test')
 
 # If buildbot improperly sets gui resource (#18365, #18441), remove it
 # so requires('gui') tests are skipped while non-gui tests still run.
 if use_resources and 'gui' in use_resources:
     try:
+        import sys
+        if sys.platform == 'darwin':
+            from lib-tk.test.runtktests import check_tk_availability
+            # tkinter.test.suppport in 3.x
+            try:
+                check_tk_availability()
+            except unittest.SkipTest:  
+                raise tk.TclError
         root = tk.Tk()
         root.destroy()
     except tk.TclError:
@@ -25,5 +35,4 @@ if __name__ == '__main__':
     # so loaded tests run the same as if textually present here.
     # If any Idle test ever needs another resource, add it to the list.
     support.use_resources = ['gui']  # use_resources is initially None
-    import unittest
     unittest.main(verbosity=2, exit=False)