test argparse with unittest and mock

问题

I have a code sample:

from argparse import ArgumentParser

class Wrapper(object):
    def __init__(self):
        self.modules = set(['gpfs_server', 'gpfs_client'])
        self.services = set(['gpfs'])

def get_opts():
    parse_wrapper = Wrapper()
    parser = ArgumentParser()

    parser.add_argument("-i", "--info", dest="show_all",
                        action = "store_true",
                        default=False,
                        help="Show supported services")
    args, unknown = parser.parse_known_args()
    args.sub_args = []
    if unknown:
        if unknown[0] not in parse_wrapper.services:
            unknown.insert(0, 'base')
        args.service = unknown[0]
        unknown.remove(unknown[0])
        args.sub_args.extend(list(unknown))
    return args

And I'm trying to write unittests for it.

from mock import patch, Mock, MagicMock
import unittest2 as unittest

import parser

class TestParser(unittest.TestCase):
    def setUp(self):
        pass

    def tearDown(self):
        reload(parser)

    @patch('parser.ArgumentParser')
    @patch('parser.Wrapper')
    def test_get_opt(self, wrp, arg):
        wrp.services = set(['gpfs'])
        args_mock = MagicMock()
        arg.return_value.add_argument = MagicMock()
        arg.return_value.parse_known_args.return_value = (args_mock, ['gpfs', 'status'])
        result = parser.get_opts()
        self.assertEqual(result, (args_mock, ['gpfs']))

But it doesn't work. First of all, it returns Namespace, so parse_known_args is not mocked. Second, it fails on assertion, as Namespace object has no dict.

self = Namespace(service='base', show_all=False, sub_args=['-v', '--cov', 'gpfs', '--junit-xml', './gpfs-coverage.xml', 'gpfs']), other = 'gpfs'

    def __eq__(self, other):
>       return vars(self) == vars(other)
E       TypeError: vars() argument must have __dict__ attribute

Where am I wrong? How argparse should be tested?

来源：https://stackoverflow.com/questions/32393206/test-argparse-with-unittest-and-mock