Refs #15902 -- Deprecated storing user's language in the session.

3 files changed, 51 insertions, 23 deletions

diff --git a/tests/auth_tests/test_views.py b/tests/auth_tests/test_views.py
index 4949ce1bf4..f738a73e64 100644
--- a/tests/auth_tests/test_views.py
+++ b/tests/auth_tests/test_views.py
@@ -31,7 +31,6 @@ from django.test import Client, TestCase, override_settings
 from django.test.client import RedirectCycleError
 from django.urls import NoReverseMatch, reverse, reverse_lazy
 from django.utils.http import urlsafe_base64_encode
-from django.utils.translation import LANGUAGE_SESSION_KEY
 
 from .client import PasswordResetConfirmClient
 from .models import CustomUser, UUIDUser
@@ -1075,16 +1074,12 @@ class LogoutTest(AuthViewsTestCase):
         self.confirm_logged_out()
 
     def test_logout_preserve_language(self):
-        """Language stored in session is preserved after logout"""
-        # Create a new session with language
-        engine = import_module(settings.SESSION_ENGINE)
-        session = engine.SessionStore()
-        session[LANGUAGE_SESSION_KEY] = 'pl'
-        session.save()
-        self.client.cookies[settings.SESSION_COOKIE_NAME] = session.session_key
-
+        """Language is preserved after logout."""
+        self.login()
+        self.client.post('/setlang/', {'language': 'pl'})
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, 'pl')
         self.client.get('/logout/')
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], 'pl')
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, 'pl')
 
     @override_settings(LOGOUT_REDIRECT_URL='/custom/')
     def test_logout_redirect_url_setting(self):
diff --git a/tests/auth_tests/urls.py b/tests/auth_tests/urls.py
index d0b259935b..142a2b49c2 100644
--- a/tests/auth_tests/urls.py
+++ b/tests/auth_tests/urls.py
@@ -9,6 +9,7 @@ from django.shortcuts import render
 from django.template import RequestContext, Template
 from django.urls import path, re_path, reverse_lazy
 from django.views.decorators.cache import never_cache
+from django.views.i18n import set_language
 
 
 class CustomRequestAuthenticationForm(AuthenticationForm):
@@ -148,6 +149,7 @@ urlpatterns = auth_urlpatterns + [
     path('permission_required_exception/', permission_required_exception),
     path('login_and_permission_required_exception/', login_and_permission_required_exception),
 
+    path('setlang/', set_language, name='set_language'),
     # This line is only required to render the password reset with is_admin=True
     path('admin/', admin.site.urls),
 ]
diff --git a/tests/view_tests/tests/test_i18n.py b/tests/view_tests/tests/test_i18n.py
index a3463a1bab..7b36181800 100644
--- a/tests/view_tests/tests/test_i18n.py
+++ b/tests/view_tests/tests/test_i18n.py
@@ -4,11 +4,12 @@ from os import path
 
 from django.conf import settings
 from django.test import (
-    RequestFactory, SimpleTestCase, TestCase, modify_settings,
+    RequestFactory, SimpleTestCase, TestCase, ignore_warnings, modify_settings,
     override_settings,
 )
 from django.test.selenium import SeleniumTestCase
 from django.urls import reverse
+from django.utils.deprecation import RemovedInDjango40Warning
 from django.utils.translation import (
     LANGUAGE_SESSION_KEY, get_language, override,
 )
@@ -36,7 +37,8 @@ class SetLanguageTests(TestCase):
         post_data = {'language': lang_code, 'next': '/'}
         response = self.client.post('/i18n/setlang/', post_data, HTTP_REFERER='/i_should_not_be_used/')
         self.assertRedirects(response, '/')
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
         # The language is set in a cookie.
         language_cookie = self.client.cookies[settings.LANGUAGE_COOKIE_NAME]
         self.assertEqual(language_cookie.value, lang_code)
@@ -53,7 +55,9 @@ class SetLanguageTests(TestCase):
         post_data = {'language': lang_code, 'next': '//unsafe/redirection/'}
         response = self.client.post('/i18n/setlang/', data=post_data)
         self.assertEqual(response.url, '/')
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, lang_code)
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
 
     def test_setlang_http_next(self):
         """
@@ -66,11 +70,15 @@ class SetLanguageTests(TestCase):
         # Insecure URL in POST data.
         response = self.client.post('/i18n/setlang/', data=post_data, secure=True)
         self.assertEqual(response.url, '/')
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, lang_code)
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
         # Insecure URL in HTTP referer.
         response = self.client.post('/i18n/setlang/', secure=True, HTTP_REFERER=non_https_next_url)
         self.assertEqual(response.url, '/')
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, lang_code)
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
 
     def test_setlang_redirect_to_referer(self):
         """
@@ -81,7 +89,9 @@ class SetLanguageTests(TestCase):
         post_data = {'language': lang_code}
         response = self.client.post('/i18n/setlang/', post_data, HTTP_REFERER='/i18n/')
         self.assertRedirects(response, '/i18n/', fetch_redirect_response=False)
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, lang_code)
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
 
     def test_setlang_default_redirect(self):
         """
@@ -92,7 +102,9 @@ class SetLanguageTests(TestCase):
         post_data = {'language': lang_code}
         response = self.client.post('/i18n/setlang/', post_data)
         self.assertRedirects(response, '/')
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, lang_code)
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
 
     def test_setlang_performs_redirect_for_ajax_if_explicitly_requested(self):
         """
@@ -102,7 +114,9 @@ class SetLanguageTests(TestCase):
         post_data = {'language': lang_code, 'next': '/'}
         response = self.client.post('/i18n/setlang/', post_data, HTTP_X_REQUESTED_WITH='XMLHttpRequest')
         self.assertRedirects(response, '/')
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, lang_code)
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
 
     def test_setlang_doesnt_perform_a_redirect_to_referer_for_ajax(self):
         """
@@ -114,7 +128,9 @@ class SetLanguageTests(TestCase):
         headers = {'HTTP_REFERER': '/', 'HTTP_X_REQUESTED_WITH': 'XMLHttpRequest'}
         response = self.client.post('/i18n/setlang/', post_data, **headers)
         self.assertEqual(response.status_code, 204)
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, lang_code)
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
 
     def test_setlang_doesnt_perform_a_default_redirect_for_ajax(self):
         """
@@ -124,7 +140,9 @@ class SetLanguageTests(TestCase):
         post_data = {'language': lang_code}
         response = self.client.post('/i18n/setlang/', post_data, HTTP_X_REQUESTED_WITH='XMLHttpRequest')
         self.assertEqual(response.status_code, 204)
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, lang_code)
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
 
     def test_setlang_unsafe_next_for_ajax(self):
         """
@@ -134,7 +152,16 @@ class SetLanguageTests(TestCase):
         post_data = {'language': lang_code, 'next': '//unsafe/redirection/'}
         response = self.client.post('/i18n/setlang/', post_data, HTTP_X_REQUESTED_WITH='XMLHttpRequest')
         self.assertEqual(response.url, '/')
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, lang_code)
+
+    def test_session_langauge_deprecation(self):
+        msg = (
+            'The user language will no longer be stored in request.session '
+            'in Django 4.0. Read it from '
+            'request.COOKIES[settings.LANGUAGE_COOKIE_NAME] instead.'
+        )
+        with self.assertRaisesMessage(RemovedInDjango40Warning, msg):
+            self.client.session[LANGUAGE_SESSION_KEY]
 
     def test_setlang_reversal(self):
         self.assertEqual(reverse('set_language'), '/i18n/setlang/')
@@ -168,7 +195,9 @@ class SetLanguageTests(TestCase):
         encoded_url = '/test-setlang/%C3%A4/'  # (%C3%A4 decodes to ä)
         response = self.client.post('/i18n/setlang/', {'language': lang_code}, HTTP_REFERER=encoded_url)
         self.assertRedirects(response, encoded_url, fetch_redirect_response=False)
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, lang_code)
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], lang_code)
 
     @modify_settings(MIDDLEWARE={
         'append': 'django.middleware.locale.LocaleMiddleware',
@@ -178,7 +207,9 @@ class SetLanguageTests(TestCase):
             '/i18n/setlang/', data={'language': 'nl'},
             follow=True, HTTP_REFERER='/en/translated/'
         )
-        self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], 'nl')
+        self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE_NAME].value, 'nl')
+        with ignore_warnings(category=RemovedInDjango40Warning):
+            self.assertEqual(self.client.session[LANGUAGE_SESSION_KEY], 'nl')
         self.assertRedirects(response, '/nl/vertaald/')
         # And reverse
         response = self.client.post(