'``POST`` to remove an invalid message'

def test_invalid_message_remove(self):

    client = self.client.login(username='john', password='blowfish')
    bef_len = Message.objects.filter(sender_deleted_at__isnull=False).count()
    response = self.client.post(reverse('userena_umessages_remove'), data={'message_pks': ['a', 'b']})
    af_len = Message.objects.filter(sender_deleted_at__isnull=False).count()
    self.assertRedirects(response, reverse('userena_umessages_list'))
    self.assertEqual(bef_len, af_len)
