Fix error in experiment tracking

If the user is not logged in, the ExperimentWaffleFlag code was
raising an exception when trying to send an event to segment.

This is a quick fix to ignore anonymous users.

lms/djangoapps/courseware/tests/test_views.py

@@ -3174,7 +3174,6 @@ class DatesTabTestCase(ModuleStoreTestCase):
 
     def setUp(self):
         super(DatesTabTestCase, self).setUp()
-        self.user = UserFactory.create()
 
         now = datetime.now(utc)
         self.course = CourseFactory.create(start=now + timedelta(days=-1))
@@ -3197,10 +3196,6 @@ class DatesTabTestCase(ModuleStoreTestCase):
 
     @RELATIVE_DATES_FLAG.override(active=True)
     def test_defaults(self):
-        request = RequestFactory().request()
-        request.user = self.user
-        self.addCleanup(crum.set_current_request, None)
-        crum.set_current_request(request)
         enrollment = CourseEnrollmentFactory(course_id=self.course.id, user=self.user, mode=CourseMode.VERIFIED)
         now = datetime.now(utc)
         with self.store.bulk_operations(self.course.id):

lms/djangoapps/experiments/flags.py

@@ -70,6 +70,10 @@ class ExperimentWaffleFlag(CourseWaffleFlag):
         if not request:
             return 0
 
+        if not request.user.id:
+            # We need username for stable bucketing and id for tracking, so just skip anonymous (not-logged-in) users
+            return 0
+
         # Use course key in experiment name to separate caches and segment calls per-course-run
         experiment_name = self.namespaced_flag_name + ('.{}'.format(course_key) if course_key else '')
 
@@ -136,7 +140,8 @@ class ExperimentWaffleFlag(CourseWaffleFlag):
 
     @contextmanager
     def override(self, active=True, bucket=1):  # pylint: disable=arguments-differ
-        from openedx.core.djangoapps.waffle_utils.testutils import override_waffle_flag
-        with override_waffle_flag(self, active):
-            with override_waffle_flag(self.bucket_flags[bucket], True):
-                yield
+        from mock import patch
+        if not active:
+            bucket = 0
+        with patch.object(self, 'get_bucket', return_value=bucket):
+            yield

lms/djangoapps/experiments/tests/test_flags.py

@@ -16,6 +16,7 @@ from experiments.factories import ExperimentKeyValueFactory
 from experiments.flags import ExperimentWaffleFlag
 from openedx.core.djangoapps.site_configuration.tests.factories import SiteFactory
 from openedx.core.djangoapps.waffle_utils import CourseWaffleFlag
+from openedx.core.djangoapps.waffle_utils.testutils import override_waffle_flag
 from student.tests.factories import CourseEnrollmentFactory, UserFactory
 from xmodule.modulestore.tests.django_utils import SharedModuleStoreTestCase
 
@@ -45,8 +46,10 @@ class ExperimentWaffleFlagTests(SharedModuleStoreTestCase):
         self.addCleanup(RequestCache.clear_all_namespaces)
 
     def get_bucket(self, track=False, active=True):
-        with self.flag.override(active=active):
-            return self.flag.get_bucket(course_key=self.key, track=track)
+        # Does not use ExperimentWaffleFlag.override, since that shortcuts get_bucket and we want to test internals
+        with override_waffle_flag(self.flag, active):
+            with override_waffle_flag(self.flag.bucket_flags[1], True):
+                return self.flag.get_bucket(course_key=self.key, track=track)
 
     def test_basic_happy_path(self):
         self.assertEqual(self.get_bucket(), 1)