Issue 24199: Deprecate idlelib.idlever with a warning on import.

Lib/idlelib/idle_test/test_warning.py

@@ -68,6 +68,15 @@ class ShellWarnTest(unittest.TestCase):
                     'Test', UserWarning, 'test_warning.py', 99, f, 'Line of code')
             self.assertEqual(shellmsg.splitlines(), f.getvalue().splitlines())
 
+class ImportWarnTest(unittest.TestCase):
+    def test_idlever(self):
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter("always")
+            import idlelib.idlever
+            self.assertEqual(len(w), 1)
+            self.assertTrue(issubclass(w[-1].category, DeprecationWarning))
+            self.assertIn("version", str(w[-1].message))
+
 
 if __name__ == '__main__':
     unittest.main(verbosity=2, exit=False)

Lib/idlelib/idlever.py

-"""Unused by Idle: there is no separate Idle version anymore.
-Kept only for possible existing extension use."""
+"""
+The separate Idle version was eliminated years ago;
+idlelib.idlever is no longer used by Idle
+and will be removed in 3.6 or later.  Use
+    from sys import version
+    IDLE_VERSION = version[:version.index(' ')]
+"""
+# Kept for now only for possible existing extension use
+import warnings as w
+w.warn(__doc__, DeprecationWarning)
 from sys import version
 IDLE_VERSION = version[:version.index(' ')]
-