Bugfix to throttling unit test

Have to use mock to properly modify throttles for unit testing
since 'override_settings' doesn't really work with the API
settings used by rest_framework.

gracedb/api/tests/test_throttling.py

-from copy import deepcopy
+import mock
 
 from django.conf import settings
 from django.core.cache import caches
@@ -8,22 +8,13 @@ from django.urls import reverse
 from api.tests.utils import GraceDbApiTestBase
 
 
-# Copy REST_FRAMEWORK settings dict and override here
-drf_settings = settings.REST_FRAMEWORK.copy()
-drf_settings['DEFAULT_THROTTLE_RATES']['anon_burst'] = '1/hour'
-
-
 class TestThrottling(GraceDbApiTestBase):
     """Test API throttles"""
 
-    def tearDown(self):
-        super(TestThrottling, self).tearDown()
-
-        # Clear throttle cache
-        caches['throttles'].clear()
-
-    @override_settings(REST_FRAMEWORK=drf_settings)
-    def test_anon_burst_throttle(self):
+    @mock.patch('api.throttling.BurstAnonRateThrottle.get_rate',
+        return_value='1/hour'
+    )
+    def test_anon_burst_throttle(self, mock_get_rate):
         """Test anonymous user burst throttle"""
         url = reverse('api:default:root')
 

gracedb/api/tests/utils.py

+from copy import deepcopy
+import mock
+
+from django.conf import settings
+from django.core.cache import caches
 from django.test import override_settings
 
 from rest_framework.test import APIClient
 
 from core.tests.utils import GraceDbTestBase
 
-# Need to allow requests without a client version header
-# to access the API for tests, unless we want to set and
-# update that header ourselves...
+
+def fix_settings(key, value):
+    """
+    Dynamically override settings for testing. But, it will only
+    ever be useful if rest_framework fixes the way that their
+    settings work so that override_settings actually works.
+
+    'key' should be x.y.z for nested dictionaries.
+    """
+    api_settings = deepcopy(settings.REST_FRAMEWORK)
+
+    key_list = key.split('.')
+    new_dict = reduce(dict.get, key_list[:-1], api_settings)
+    new_dict[key_list[-1]] = value
+
+    return api_settings
+
+
+@mock.patch('api.throttling.BurstAnonRateThrottle.get_rate',
+    return_value='1000/second'
+)
 @override_settings(
     ALLOW_BLANK_USER_AGENT_TO_API=True,
 )
 class GraceDbApiTestBase(GraceDbTestBase):
     client_class = APIClient
+
+    def tearDown(self):
+        super(GraceDbApiTestBase, self).tearDown()
+
+        # Clear throttle cache
+        caches['throttles'].clear()