decorators don't play nice with nose?

[hyperboreean]

Hi, I am trying to test the business part of a web service. For this I 
am using unittest & nose.
I wrote a decorator that should handle the xml test file retrieval, but 
it seems I can't get it working with nose.
Here's the code:


* MyApp.py -- base test class *

import os
import unittest

from MyApp.Core import XmlParser


__all__ = ['MyAppTest', 'setup']


PATH = os.path.dirname(__file__) or ''


class setup(object):
    """Decorator to ease the use of xml files in MyApp tests.

    The way it works it that it decorates a test method which has a first
    default parameter called 'parser' and it overwrites this parameter value
    with a XmlParser instance.

    The xml file should be located under:
    data/testedBusinessRequest/testMethodName.xml
    """
    def __init__(self, testedBusinessRequest = ''):
        self.testedBusinessRequest =\
                testedBusinessRequest.lower()


    def _getXmlParser(self, xml):
        documentElement = XmlParser.parseXmlStream(xml)
        parser = XmlParser.getParser(documentElement)
        return parser


    def __call__(self, method):

        # TODO: error handling here
        methodName = method.func_code.co_name
        methodName = methodName.split('_')[1]

        xmlFolder = self.testedBusinessRequest
        xmlFile = '%s.xml' % methodName

        path = os.path.join(PATH, 'data',
                xmlFolder, xmlFile)

        f = open(path)
        xml = f.read()
        f.close()
        method.func_defaults = (self._getXmlParser(xml),)
        return method


class MyAppTest(unittest.TestCase):

    def setUp(self):
        self.database = Database()

    def tearDown(self):
        pass


* test_Login.py - test a business request *
from MyAppTest import MyAppTest, setup

from MyApp import Login


class TestLogin(MyAppTest):
    testedBusinessRequest = 'Login'

    @setup(testedBusinessRequest)
    def test_validParameters(self, parser = None):
        response = Login(self.database, parser).run()
        return True



Ok, so the decorator setup should fill the parser parameter with a 
XmlParser object. This works well if I add a __main__ and use unittest 
to run the tests. But if I use nose, I get the following error:

*TypeError: unbound method __call__() must be called with setup instance 
as first argument (got module instance instead)*

Any advices?
Thanks!