Improving property to accept abstract methods

Lib/test/test_property.py

 # Test case for property
 # more tests are in test_descr
 
 import sys
 import unittest
 from test.support import run_unittest
 
 class PropertyBase(Exception):
     pass
 
@@ skipping 109 matching lines @@
 
     @unittest.skipIf(sys.flags.optimize >= 2,
                      "Docstrings are omitted with -O2 and above")
     def test_property_getter_doc_override(self):
         newgettersub = PropertySubNewGetter()
         self.assertEqual(newgettersub.spam, 5)
         self.assertEqual(newgettersub.__class__.spam.__doc__, "new docstring")
         newgetter = PropertyNewGetter()
         self.assertEqual(newgetter.spam, 8)
         self.assertEqual(newgetter.__class__.spam.__doc__, "new docstring")
+
+    def test_property___isabstractmethod__descriptor(self):
+        for val in (True, False, [], [1], '', '1'):
+            class C(object):
+                def foo(self):
+                    pass
+                foo.__isabstractmethod__ = val
+                foo = property(foo)
+            self.assertIs(C.foo.__isabstractmethod__, bool(val))
+
+        # check that the property's __isabstractmethod__ descriptor does the
+        # right thing when presented with a value that fails truth testing:
+        class NotBool(object):
+            def __nonzero__(self):
+                raise ValueError()
+            __len__ = __nonzero__
+        with self.assertRaises(ValueError):
+            class C(object):
+                def foo(self):
+                    pass
+                foo.__isabstractmethod__ = NotBool()
+                foo = property(foo)
+            C.foo.__isabstractmethod__
 
 
 # Issue 5890: subclasses of property do not preserve method __doc__ strings
 class PropertySub(property):
     """This is a subclass of property"""
 
 class PropertySubSlots(property):
     """This is a subclass of property that defines __slots__"""
     __slots__ = ()
 
@@ skipping 82 matching lines @@
                 return 2
         self.assertEqual(Foo.spam.__doc__, "a new docstring")
 
 
 
 def test_main():
     run_unittest(PropertyTests, PropertySubclassTests)
 
 if __name__ == '__main__':
     test_main()