Why don't my Django unittests know that MessageMiddleware is installed?

Question

I\'m working on a Django project and am writing unittests for it. However, in a test, when I try and log a user in, I get this error:

MessageFailure: You can         


        

Answer 1

Django 1.4 has a bug when you create the request with RequestFactory.

To resolve this issue, create your request with RequestFactory and do this:

from django.contrib.messages.storage.fallback import FallbackStorage
setattr(request, 'session', 'session')
messages = FallbackStorage(request)
setattr(request, '_messages', messages)

Works for me!

Answer 2

In my case (django 1.8) this problem occurs in when unit-test calls signal handler for user_logged_in signal, looks like messages app has not been called, i.e. request._messages is not yet set. This fails:

from django.contrib.auth.signals import user_logged_in
...

@receiver(user_logged_in)
def user_logged_in_handler(sender, user, request, **kwargs):

    ...
    messages.warning(request, "user has logged in")

the same call to messages.warning in normal view function (that is called after) works without any issues.

A workaround I based on one of the suggestions from https://code.djangoproject.com/ticket/17971, use fail_silently argument only in signal handler function, i.e. this solved my problem:

messages.warning(request, "user has logged in",
                 fail_silently=True )

Answer 3

This happened to me in the login_callback signal receiver function when called from a unit test, and the way around the problem was:

from django.contrib.messages.storage import default_storage

@receiver(user_logged_in)
def login_callback(sender, user, request, **kwargs):
    if not hasattr(request, '_messages'):  # fails for tests
        request._messages = default_storage(request)

Django 2.0.x

Answer 4

This builds on Tarsis Azevedo's answer by creating a MessagingRequest helper class below.

Given say a KittenAdmin I'd want to get 100% test coverage for:

from django.contrib import admin, messages

class KittenAdmin(admin.ModelAdmin):
    def warm_fuzzy_method(self, request):
        messages.warning(request, 'Can I haz cheezburger?')

I created a MessagingRequest helper class to use in say a test_helpers.py file:

from django.contrib.messages.storage.fallback import FallbackStorage
from django.http import HttpRequest

class MessagingRequest(HttpRequest):
    session = 'session'

    def __init__(self):
        super(MessagingRequest, self).__init__()
        self._messages = FallbackStorage(self)

    def get_messages(self):
        return getattr(self._messages, '_queued_messages')

    def get_message_strings(self):
        return [str(m) for m in self.get_messages()]

Then in a standard Django tests.py:

from django.contrib.admin.sites import AdminSite
from django.test import TestCase

from cats.kitten.admin import KittenAdmin
from cats.kitten.models import Kitten
from cats.kitten.test_helpers import MessagingRequest

class KittenAdminTest(TestCase):
    def test_kitten_admin_message(self):
        admin = KittenAdmin(model=Kitten, admin_site=AdminSite())
        expect = ['Can I haz cheezburger?']
        request = MessagingRequest()
        admin.warm_fuzzy_method(request)
        self.assertEqual(request.get_message_strings(), expect)

Results:

coverage run --include='cats/kitten/*' manage.py test; coverage report -m
Creating test database for alias 'default'...
.
----------------------------------------------------------------------
Ran 1 test in 0.001s

OK
Destroying test database for alias 'default'...
Name                                     Stmts   Miss  Cover   Missing
----------------------------------------------------------------------
cats/kitten/__init__.py                      0      0   100%   
cats/kitten/admin.py                         4      0   100%   
cats/kitten/migrations/0001_initial.py       5      0   100%   
cats/kitten/migrations/__init__.py           0      0   100%   
cats/kitten/models.py                        3      0   100%   
cats/kitten/test_helpers.py                 11      0   100%   
cats/kitten/tests.py                        12      0   100%   
----------------------------------------------------------------------
TOTAL                                       35      0   100%   

Answer 5

A way to solve this quite elegant is to mock the messages module using mock

Say you have a class based view named FooView in app named myapp

from django.contrib import messages
from django.views.generic import TemplateView

class FooView(TemplateView):
    def post(self, request, *args, **kwargs):
        ...
        messages.add_message(request, messages.SUCCESS, '\o/ Profit \o/')
        ...

You now can test it with

def test_successful_post(self):
    mock_messages = patch('myapp.views.FooView.messages').start()
    mock_messages.SUCCESS = success = 'super duper'
    request = self.rf.post('/', {})
    view = FooView.as_view()
    response = view(request)
    msg = _(u'\o/ Profit \o/')
    mock_messages.add_message.assert_called_with(request, success, msg)

Answer 6

I found when I had a problem patching messages the solution was to patch the module from within the class under test (obsolete Django version BTW, YMMV). Pseudocode follows.

my_module.py:

from django.contrib import messages


class MyClass:

    def help(self):
        messages.add_message(self.request, messages.ERROR, "Foobar!")

test_my_module.py:

from unittest import patch, MagicMock
from my_module import MyClass


class TestMyClass(TestCase):

    def test_help(self):
        with patch("my_module.messages") as mock_messages:
            mock_messages.add_message = MagicMock()
            MyClass().help()  # shouldn't complain about middleware