Django test Client can only login once?

Question

Our team is currently writing tests for our application. I am currently writing code to acces the views. These views are behind a login-screen, so our test first have to login and than peform the rest of the test. I've run into a very strange error. Basically My tests can only login once.

As you can see in the example below, both classes are doing the exact same thing, yet only one of them succeeds with the login, the other gives a '302 doest not equal 200' assertion error.

If I comment out the bottom one, the one at the top works, and vice versa. Code that is testing different views also doesnt work, unless I comment out all other tests.

It doesnt matter if I login like shown below, or use a different variant (like self.client.login(username='test', password='password')).

Me and my team have no idea why Django is behaving this way and what we are doing wrong. Its almost as if the connection remains open and we would have to add code to close it. But the django-documentation doesnt mention any of this. DOes anyone know what we are doing wrong?

class FunctieListView_tests(TestCase):
"""Function listview only shows the data for the current_user / tenant"""

def setUp(self):
    self.tenant = get_tenant()
    self.function = get_function(self.tenant)
    self.client = Client(HTTP_HOST='tc.tc:8000')
    self.user = get_user(self.tenant)


def test_correct_function_context(self):
    # Test if the view is only displaying the correct context data
    self.client.post(settings.LOGIN_URL, {
        'username': self.user.username,
        'password': 'password'
    }, HTTP_HOST='tc.tc:8000')
    response = self.client.get(reverse('functie_list'))
    self.assertEqual(response.status_code, 200)
    self.assertTrue(response.context['functie_templates'] != None)
    self.assertEqual(response.context['functie_templates'][0],
                     FunctieTemplate.objects.filter(linked_tenant=self.tenant)[0])


class FunctieListView_2_tests(TestCase):
"""Role Listview only shows the data for the current_user / tenant"""

def setUp(self):
    self.tenant = get_tenant()
    self.function = get_function(self.tenant)
    self.client = Client(HTTP_HOST='tc.tc:8000')
    self.user = get_user(self.tenant)

def test_correct_function_context_second(self):
    #login
    # Test if the view is only displaying the correct context data
    self.client.post(settings.LOGIN_URL, {
        'username': self.user.username,
        'password': 'password'
    }, HTTP_HOST='tc.tc:8000')
    response = self.client.get(reverse('functie_list'))
    self.assertEqual(response.status_code, 200)
    self.assertTrue(response.context['functie_templates'] != None)
    self.assertEqual(response.context['functie_templates'][0],
                     FunctieTemplate.objects.filter(linked_tenant=self.tenant)[0])

The users, tenants and functions are defined in a seperate utils file like so:

def get_user(tenant, name='test'):

    u = User.objects.create_user(name, '{}@test.test'.format(name), 'password')
    u.save()
    u.profile.tenant = tenant
    u.profile.tenant_role = generis.models.TENANT_OWNER
    u.profile.save()
    return u


def get_function(tenant):

    userfunction = UserFunction.objects.create(name='test_functie', linked_tenant=tenant)
    userfunction.save()
    return userfunction


def get_tenant(slug_var='tc'):
    f = elearning.models.FontStyle(font='foobar')
    f.save()
    c = elearning.models.ColorScheme(name='foobar', title='foo', text='fleeb', background='juice', block_background='schleem', box='plumbus')
    c.save()
    t = elearning.models.Tenant(name='tc', slug=slug_var, default_font_style=f, default_color_scheme=c)
    t.save()
    return t

Answer 1

My guess is that it happens because you are instantiating the Client yourself in setUp. Although it looks fine the outcome is obviously different from the regular behavior. I never had problems with login using the preinitialized self.client of django.test.TestCase.

Looking at django.test.client.Client, it says in the inline documentation:

Client objects are stateful - they will retain cookie (and thus session) details for the lifetime of the Client instance.

and a still existing cookie would explain the behavior you describe.

I cannot find HTTP_HOST in django.test.client.py, so I'm not sure whether you are really using that Client class at all. If you need access to a live server instance during tests, you could use Django's LiveServerTestCase.