On OS X 10.6.8, I'm getting the following result for test_socket:

[cpython] % ./python.exe -m test test_socket
[1/1] test_socket
/Users/geoff/Documents/programming/cpython/Lib/test/test_socket.py:1721: RuntimeWarning: received malformed or improperly-truncated ancillary data
  result = sock.recvmsg(bufsize, *args)
/Users/geoff/Documents/programming/cpython/Lib/test/test_socket.py:1812: RuntimeWarning: received malformed or improperly-truncated ancillary data
  result = sock.recvmsg_into([buf], *args)
test test_socket failed -- Traceback (most recent call last):
  File "/Users/geoff/Documents/programming/cpython/Lib/test/test_socket.py", line 1169, in testGetaddrinfo
    socket.getaddrinfo("localhost", None, 0, 0, 0, socket.AI_NUMERICSERV)
socket.gaierror: [Errno 8] nodename nor servname provided, or not known

1 test failed:
test_socket

According to the OS X manpage for getaddrinfo(3), (and RFC 3493) this error is the expected behavior for a POSIX socket implementation:

                AI_NUMERICSERV  If the AI_NUMERICSERV bit is set, then a
                                non-null servname string supplied shall be
                                a numeric port string.  Otherwise, an
                                EAI_NONAME error shall be returned.  This
                                bit shall prevent any type of name resolu-
                                tion service (for example, NIS+) from
                                being invoked.

(servname is the 2nd argument to getaddrinfo(), where the test passes None. EAI_NONAME is Errno 8.)

Confirmed on 2.7.6, 3.3 and current HEAD of 3.4; the offending test code didn't exist in 3.2 and earlier.

The test works for me on OS X 10.6 and OS X 10.9. My guess is that the problem you are seeing is due to a failing lookup of "localhost". What does your Python report for:

socket.gethostbyname("localhost")

The getaddrinfo(3) man page description does not really cover the case here since Python's socketmodule.c contains a workaround to prevent an OS X segfault (bpo-17269) so the test that is failing is actually equivalent to:

socket.getaddrinfo("localhost", "00", 0, 0, 0, socket.AI_NUMERICSERV)

The equivalent C code executes without error on my systems regardless whether it is meaningful.

Ned:

>>> socket.gethostbyname("localhost")
'127.0.0.1'

>>> socket.getaddrinfo("localhost", "00", 0, 0, 0, socket.AI_NUMERICSERV)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.4/socket.py", line 530, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno 8] nodename nor servname provided, or not known

And to show that using AI_NUMERICSERV isn't *completely* broken on my machine:

>>> socket.getaddrinfo("localhost", "80", 0, 0, 0, socket.AI_NUMERICSERV)
[(<AddressFamily.AF_INET: 2>, <SocketType.SOCK_DGRAM: 2>, 17, '', ('127.0.0.1', 80)), (<AddressFamily.AF_INET: 2>, <SocketType.SOCK_STREAM: 1>, 6, '', ('127.0.0.1', 80)), (<AddressFamily.AF_INET6: 30>, <SocketType.SOCK_DGRAM: 2>, 17, '', ('::1', 80, 0, 0)), (<AddressFamily.AF_INET6: 30>, <SocketType.SOCK_STREAM: 1>, 6, '', ('::1', 80, 0, 0)), (<AddressFamily.AF_INET6: 30>, <SocketType.SOCK_DGRAM: 2>, 17, '', ('fe80::1%lo0', 80, 0, 1)), (<AddressFamily.AF_INET6: 30>, <SocketType.SOCK_STREAM: 1>, 6, '', ('fe80::1%lo0', 80, 0, 1))]

OK, OK, it's not just your machine :=) I was finally able to reproduce the same failure on a different 10.6 system. I'm still not sure what the difference between them is but it really doesn't matter. I have a patch forthcoming to make the test work in either case.

New changeset 6017d19669c3 by Ned Deily in branch '2.7':
Issue bpo-20605: Make test_socket getaddrinfo OS X segfault test more robust.
http://hg.python.org/cpython/rev/6017d19669c3

New changeset 11a75f141cec by Ned Deily in branch '3.3':
Issue bpo-20605: Make test_socket getaddrinfo OS X segfault test more robust.
http://hg.python.org/cpython/rev/11a75f141cec

New changeset 378bdb92e5b7 by Ned Deily in branch 'default':
Issue bpo-20605: Make test_socket getaddrinfo OS X segfault test more robust.
http://hg.python.org/cpython/rev/378bdb92e5b7

The committed changes should prevent spurious test failures. Thanks for the report.