Rate limit course list API.

This endpoint is likely being inefficient with how it's querying various parts
of the code and can take courseware down, it needs to be rate limited until
optimized.

LEARNER-5527

lms/djangoapps/course_api/tests/test_views.py

@@ -1,8 +1,10 @@
 """
 Tests for Course API views.
 """
+import ddt
 from hashlib import md5
 
+from django.core.exceptions import ImproperlyConfigured
 from django.urls import reverse
 from django.test import RequestFactory
 from django.test.utils import override_settings
@@ -12,8 +14,9 @@ from search.tests.tests import TEST_INDEX_NAME
 from search.tests.utils import SearcherMixin
 
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase, SharedModuleStoreTestCase
+from waffle.testutils import override_switch
 
-from ..views import CourseDetailView
+from ..views import CourseDetailView, CourseListUserThrottle
 from .mixins import TEST_PASSWORD, CourseApiFactoryMixin
 
 
@@ -53,6 +56,7 @@ class CourseApiTestViewMixin(CourseApiFactoryMixin):
 
 
 @attr(shard=9)
+@ddt.ddt
 class CourseListViewTestCase(CourseApiTestViewMixin, SharedModuleStoreTestCase):
     """
     Test responses returned from CourseListView.
@@ -100,6 +104,38 @@ class CourseListViewTestCase(CourseApiTestViewMixin, SharedModuleStoreTestCase):
         self.client.logout()
         self.verify_response()
 
+    def assert_throttle_configured_correctly(self, user_scope, throws_exception, expected_rate):
+        """Helper to determine throttle configuration is correctly set."""
+        throttle = CourseListUserThrottle()
+        throttle.check_for_switches()
+        throttle.scope = user_scope
+        try:
+            rate_limit, __ = throttle.parse_rate(throttle.get_rate())
+            self.assertEqual(rate_limit, expected_rate)
+            self.assertFalse(throws_exception)
+        except ImproperlyConfigured:
+            self.assertTrue(throws_exception)
+
+    @ddt.data(('staff', False, 40), ('user', False, 20), ('unknown', True, None))
+    @ddt.unpack
+    def test_throttle_rate_default(self, user_scope, throws_exception, expected_rate):
+        """ Make sure throttle rate default is set correctly for different user scopes. """
+        self.assert_throttle_configured_correctly(user_scope, throws_exception, expected_rate)
+
+    @ddt.data(('staff', False, 10), ('user', False, 2), ('unknown', True, None))
+    @ddt.unpack
+    @override_switch('course_list_api_rate_limit.rate_limit_2', active=True)
+    def test_throttle_rate_2(self, user_scope, throws_exception, expected_rate):
+        """ Make sure throttle rate 2 is set correctly for different user scopes. """
+        self.assert_throttle_configured_correctly(user_scope, throws_exception, expected_rate)
+
+    @ddt.data(('staff', False, 20), ('user', False, 10), ('unknown', True, None))
+    @ddt.unpack
+    @override_switch('course_list_api_rate_limit.rate_limit_10', active=True)
+    def test_throttle_rate_20(self, user_scope, throws_exception, expected_rate):
+        """ Make sure throttle rate 20 is set correctly for different user scopes. """
+        self.assert_throttle_configured_correctly(user_scope, throws_exception, expected_rate)
+
 
 @attr(shard=9)
 class CourseListViewTestCaseMultipleCourses(CourseApiTestViewMixin, ModuleStoreTestCase):