Add directory which contains known ref leaks. Some of these are likely to be...

Add directory which contains known ref leaks.  Some of these are likely to be system dependent (like test_gestalt).

Lib/test/leakers/README

+This directory contains test cases that are known to leak references.
+The idea is that you can import these modules while in the interpreter
+and call the leak function repeatedly.  This will only be helpful if
+the interpreter was built in debug mode.  If the total ref count
+doesn't increase, the bug has been fixed.
+
+Here's an example interpreter session for test_gestalt which still leaks:
+
+>>> from test.leakers.test_gestalt import leak
+[24275 refs]
+>>> leak()
+[28936 refs]
+>>> leak()
+[28938 refs]
+>>> leak()
+[28940 refs]
+>>> 
+

Lib/test/leakers/test_gestalt.py

+
+import sys
+
+if sys.platform != 'darwin':
+    raise ValueError, "This test only leaks on Mac OS X'
+
+def leak():
+    # taken from platform._mac_ver_lookup()
+    from gestalt import gestalt
+    import MacOS
+
+    try:
+        gestalt('sysu')
+    except MacOS.Error:
+        pass

Lib/test/leakers/test_tee.py

+
+# Test case taken from test_itertools
+# See http://mail.python.org/pipermail/python-dev/2005-November/058339.html
+
+from itertools import tee
+
+def leak():
+    def fib():
+        def yield_identity_forever(g):
+            while 1:
+                yield g
+        def _fib():
+            for i in yield_identity_forever(head):
+                yield i
+        head, tail, result = tee(_fib(), 3)
+        return result
+
+    x = fib()
+    x.next()