Testing Python Decorators?

Question

I'm writing some unit tests for a Django project, and I was wondering if its possible (or necessary?) to test some of the decorators that I wrote for it.

Here is an example of a decorator that I wrote:

class login_required(object):

    def __init__(self, f):
        self.f = f

    def __call__(self, *args):
        request = args[0]
        if request.user and request.user.is_authenticated():
            return self.f(*args)
        return redirect('/login')

Answer 1

Simply:

from nose.tools import assert_equal
from mock import Mock

class TestLoginRequired(object):
    def test_no_user(self):
        func = Mock()
        decorated_func = login_required(func)
        request = prepare_request_without_user()
        response = decorated_func(request)
        assert not func.called
        # assert response is redirect

    def test_bad_user(self):
        func = Mock()
        decorated_func = login_required(func)
        request = prepare_request_with_non_authenticated_user()
        response = decorated_func(request)
        assert not func.called
        # assert response is redirect

    def test_ok(self):
        func = Mock(return_value='my response')
        decorated_func = login_required(func)
        request = prepare_request_with_ok_user()
        response = decorated_func(request)
        func.assert_called_with(request)
        assert_equal(response, 'my response')

The mock library helps here.