@classmethod<EOL><INDENT>def setUpClass(cls):<DEDENT>
if "<STR_LIT>" not in _support.RESOURCES:<EOL><INDENT>raise unittest.SkipTest("<STR_LIT>")<EOL><DEDENT>try:<EOL><INDENT>sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)<EOL>sock.close()<EOL>cls.can_do_ipv4 = True<EOL><DEDENT>except socket.error as err:<EOL><INDENT>logger.debug("<STR_LIT>".format(err))<EOL>pass<EOL><DEDENT>if socket.has_ipv6:<EOL><INDENT>try:<EOL><INDENT>sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)<EOL>sock.close()<EOL>cls.can_do_ipv6 = True<EOL><DEDENT>except socket.error as err:<EOL><INDENT>logger.debug("<STR_LIT>".format(err))<EOL>pass<EOL><DEDENT><DEDENT>
Check if loopback networking is enabled and IPv4 and IPv6 sockets
        available.