Add support for python >= 3.4

Python 3.4 changed some of the output from argparse and the
handling of default func and command behaviour; this patch
deals with both < and >= 3.4 behaviour.

Change-Id: I27983f7b06fc16aeedb98a4b36f7ff9a451706ec
Closes-Bug: 1496805

magnumclient/shell.py

@@ -420,7 +420,8 @@ class OpenStackMagnumShell(object):
         args = subcommand_parser.parse_args(argv)
 
         # Short-circuit and deal with help right away.
-        if args.func == self.do_help:
+        # NOTE(jamespage): args.func is not guaranteed with python >= 3.4
+        if not hasattr(args, 'func') or args.func == self.do_help:
             self.do_help(args)
             return 0
         elif args.func == self.do_bash_completion:
@@ -551,7 +552,10 @@ class OpenStackMagnumShell(object):
                   help='Display help for <subcommand>.')
     def do_help(self, args):
         """Display help about this program or one of its subcommands."""
-        if args.command:
+        # NOTE(jamespage): args.command is not guaranteed with python >= 3.4
+        command = getattr(args, 'command', '')
+
+        if command:
             if args.command in self.subcommands:
                 self.subcommands[args.command].print_help()
             else:

magnumclient/tests/test_shell_args.py

@@ -36,13 +36,13 @@ class TestCommandLineArgument(utils.TestCase):
 
     _mandatory_arg_error = [
         '.*?^usage: ',
-        '.*?^error: argument',
+        '.*?^error: (the following arguments|argument)',
         ".*?^Try 'magnum help ",
         ]
 
     _few_argument_error = [
         '.*?^usage: magnum ',
-        '.*?^error: too few arguments',
+        '.*?^error: (the following arguments|too few arguments)',
         ".*?^Try"
         ]
 
@@ -189,7 +189,7 @@ class TestCommandLineArgument(utils.TestCase):
     def test_bay_update_failure_few_args(self, mock_update):
         _error_msg = [
             '.*?^usage: magnum bay-update ',
-            '.*?^error: too few arguments',
+            '.*?^error: (the following arguments|too few arguments)',
             ".*?^Try 'magnum help bay-update' for more information."
             ]
         self._test_arg_failure('bay-update', _error_msg)

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 1.6
-envlist = py26,py27,py33,pypy,pep8
+envlist = py26,py27,py33,py34,pypy,pep8
 skipsdist = True
 
 [testenv]