Django testing how to assert Redirect

Question

With the folliwing code I get this wrong result : nose.proxy.AssertionError: 302 != 200 : Couldn't retrieve redirection page '/mes_dossiers/': response code was 302 (expected 200)

what is wrong with my code ?

#test.py
from django.test import TestCase, RequestFactory, Client
from ..models import *
from ..views import *
from django.core.management import call_command

class Cas(TestCase):

    def setUp(self):
        call_command('loaddata', 'fixture_users.json', verbosity=1)
        call_command('loaddata', 'xxxxx_tests_xxxx.yaml', 
        verbosity=1)

    def test_dossier_duplicate(self) :
        request = self.factory.get('/dossier/3/copier/', follow = True)
        request.user = User.objects.get(id=3)
        pk = 3
        response = dossier_duplicate(request, pk)
        response.client = Client()
        self.assertRedirects(response,'/mes_dossiers/',status_code=302, 
        target_status_code=200)

#urls.py
urlpatterns = [    
url(r'^dossier/(?P<pk>[0-9]+)/copier/$',views.dossier_duplicate),  

]

#views.py
@login_required(login_url="/accounts/login/")
def dossier_duplicate(request, pk):

    dossier = get_object_or_404(Dossier, pk=pk)
    groupe = dossier.createdBy.groups.all()[0].name

    if not in_group(request.user, groupe) :
        return HttpResponseForbidden('Vous ne pouvez pas accéder à ce 
        dossier')

    else :

        #code to duplicate the "dossier" instance and child contents
        #
        #

        return redirect('/mes_dossiers/')

Answer 1

I've found more examples there:

Django : Testing if the page has redirected to the desired url

https://docs.djangoproject.com/en/3.0/topics/testing/tools/#django.test.SimpleTestCase.assertRedirects

and this worked:

class Cas(TestCase):

    def setUp(self):
        call_command('loaddata', 'fixture_users.json', verbosity=1)
        call_command('loaddata', 'xxx_tests_xxxx.yaml', 
        verbosity=1)

    def test_dossier_duplicate(self) :
        request = self.client.get('/dossier/3/copier/', follow = True)
        request.user = User.objects.get(id=3)
        pk = 3
        response = dossier_duplicate(request, pk)
        response.client = Client()
        response.client.login(username='xxxx', password='xxxxx')

        self.assertRedirects(response, '/mes_dossiers/', status_code=302, 
        target_status_code=200, fetch_redirect_response=True)