Capture the language preference set by an anonymous user when the register or login

[LEARNER-168]

common/djangoapps/student/tests/factories.py

@@ -84,9 +84,11 @@ class UserFactory(DjangoModelFactory):
         model = User
         django_get_or_create = ('email', 'username')
 
+    _DEFAULT_PASSWORD = 'test'
+
     username = factory.Sequence(u'robot{0}'.format)
     email = factory.Sequence(u'robot+test+{0}@edx.org'.format)
-    password = factory.PostGenerationMethodCall('set_password', 'test')
+    password = factory.PostGenerationMethodCall('set_password', _DEFAULT_PASSWORD)
     first_name = factory.Sequence(u'Robot{0}'.format)
     last_name = 'Test'
     is_staff = False

openedx/core/djangoapps/lang_pref/middleware.py

@@ -32,6 +32,8 @@ class LanguagePreferenceMiddleware(object):
         if cookie_lang:
             if request.user.is_authenticated():
                 set_user_preference(request.user, LANGUAGE_KEY, cookie_lang)
+            else:
+                request._anonymous_user_cookie_lang = cookie_lang
 
             accept_header = request.META.get(LANGUAGE_HEADER, None)
             if accept_header:
@@ -51,25 +53,32 @@ class LanguagePreferenceMiddleware(object):
     def process_response(self, request, response):
         # If the user is logged in, check for their language preference
         if getattr(request, 'user', None) and request.user.is_authenticated():
-            # Get the user's language preference
-            try:
-                user_pref = get_user_preference(request.user, LANGUAGE_KEY)
-            except (UserAPIRequestError, UserAPIInternalError):
-                # If we can't find the user preferences, then don't modify the cookie
-                pass
+            user_pref = None
+
+            anonymous_cookie_lang = getattr(request, '_anonymous_user_cookie_lang', None)
+            if anonymous_cookie_lang:
+                user_pref = anonymous_cookie_lang
+                set_user_preference(request.user, LANGUAGE_KEY, anonymous_cookie_lang)
             else:
-                # Set it in the LANGUAGE_COOKIE
-                if user_pref:
-                    response.set_cookie(
-                        settings.LANGUAGE_COOKIE,
-                        value=user_pref,
-                        domain=settings.SESSION_COOKIE_DOMAIN,
-                        max_age=COOKIE_DURATION,
-                    )
-                else:
-                    response.delete_cookie(
-                        settings.LANGUAGE_COOKIE,
-                        domain=settings.SESSION_COOKIE_DOMAIN
-                    )
+                # Get the user's language preference
+                try:
+                    user_pref = get_user_preference(request.user, LANGUAGE_KEY)
+                except (UserAPIRequestError, UserAPIInternalError):
+                    # If we can't find the user preferences, then don't modify the cookie
+                    pass
+
+            # If set, set the user_pref in the LANGUAGE_COOKIE
+            if user_pref:
+                response.set_cookie(
+                    settings.LANGUAGE_COOKIE,
+                    value=user_pref,
+                    domain=settings.SESSION_COOKIE_DOMAIN,
+                    max_age=COOKIE_DURATION,
+                )
+            else:
+                response.delete_cookie(
+                    settings.LANGUAGE_COOKIE,
+                    domain=settings.SESSION_COOKIE_DOMAIN
+                )
 
         return response

openedx/core/djangoapps/lang_pref/tests/test_middleware.py

@@ -168,6 +168,54 @@ class TestUserPreferenceMiddleware(TestCase):
         else:
             self.assertNotIn(settings.LANGUAGE_COOKIE, self.client.cookies)
 
+    @ddt.data(
+        (None, None),
+        ('es', 'es-419'),
+        ('en', 'en'),
+        ('es-419', 'es-419')
+    )
+    @ddt.unpack
+    def test_login_captures_lang_pref(self, lang_cookie, expected_lang):
+        if lang_cookie:
+            self.client.cookies[settings.LANGUAGE_COOKIE] = lang_cookie
+        elif settings.LANGUAGE_COOKIE in self.client.cookies:
+            del self.client.cookies[settings.LANGUAGE_COOKIE]
+
+        # Use an actual call to the login endpoint, to validate that the middleware
+        # stack does the right thing
+        if settings.FEATURES.get('ENABLE_COMBINED_LOGIN_REGISTRATION'):
+            response = self.client.post(
+                reverse('user_api_login_session'),
+                data={
+                    'email': self.user.email,
+                    'password': UserFactory._DEFAULT_PASSWORD,
+                    'remember': True,
+                }
+            )
+        else:
+            response = self.client.post(
+                reverse('login_post'),
+                data={
+                    'email': self.user.email,
+                    'password': UserFactory._DEFAULT_PASSWORD,
+                    'honor_code': True,
+                }
+            )
+
+        self.assertEqual(response.status_code, 200)
+
+        if lang_cookie:
+            self.assertEqual(response['Content-Language'], expected_lang)
+            self.assertEqual(get_user_preference(self.user, LANGUAGE_KEY), lang_cookie)
+            self.assertEqual(
+                self.client.cookies[settings.LANGUAGE_COOKIE].value,
+                lang_cookie
+            )
+        else:
+            self.assertEqual(response['Content-Language'], 'en')
+            self.assertEqual(get_user_preference(self.user, LANGUAGE_KEY), None)
+            self.assertEqual(self.client.cookies[settings.LANGUAGE_COOKIE].value, '')
+
     def test_process_response_no_user_noop(self):
         del self.request.user
         response = mock.Mock(spec=HttpResponse)