Issue #3680: Reference cycles created through a dict, set or deque iterator did not get collected.

1 files changed, 15 insertions, 2 deletions

diff --git a/Lib/test/test_set.py b/Lib/test/test_set.py
index d38a675..8d05712 100644
--- a/Lib/test/test_set.py
+++ b/Lib/test/test_set.py
@@ -1,6 +1,7 @@
 import unittest
 from test import test_support
-from weakref import proxy
+import gc
+import weakref
 import operator
 import copy
 import pickle
@@ -322,6 +323,18 @@ class TestJointOps(unittest.TestCase):
         self.assertEqual(sum(elem.hash_count for elem in d), n)
         self.assertEqual(d3, dict.fromkeys(d, 123))
 
+    def test_container_iterator(self):
+        # Bug # XXX: tp_traverse was not implemented for set iterator object
+        class C(object):
+            pass
+        obj = C()
+        ref = weakref.ref(obj)
+        container = set([obj, 1])
+        obj.x = iter(container)
+        del obj, container
+        gc.collect()
+        self.assert_(ref() is None, "Cycle was not collected")
+
 class TestSet(TestJointOps):
     thetype = set
 
@@ -538,7 +551,7 @@ class TestSet(TestJointOps):
 
     def test_weakref(self):
         s = self.thetype('gallahad')
-        p = proxy(s)
+        p = weakref.proxy(s)
         self.assertEqual(str(p), str(s))
         s = None
         self.assertRaises(ReferenceError, str, p)