Add test checking override_settings compat

tests/test_settings.py

@@ -1,8 +1,8 @@
 from __future__ import unicode_literals
 
-from django.test import TestCase
+from django.test import TestCase, override_settings
 
-from rest_framework.settings import APISettings
+from rest_framework.settings import APISettings, api_settings
 
 
 class TestSettings(TestCase):
@@ -28,6 +28,23 @@ def test_warning_raised_on_removed_setting(self):
                 'MAX_PAGINATE_BY': 100
             })
 
+    def test_compatibility_with_override_settings(self):
+        """
+        Ref #5658 & #2466: Documented usage of api_settings
+        is bound at import time:
+
+            from rest_framework.settings import api_settings
+
+        setting_changed signal hook must ensure bound instance
+        is refreshed.
+        """
+        assert api_settings.PAGE_SIZE is None, "Checking a known default should be None"
+
+        with override_settings(REST_FRAMEWORK={'PAGE_SIZE': 10}):
+            assert api_settings.PAGE_SIZE == 10, "Setting should have been updated"
+
+        assert api_settings.PAGE_SIZE is None, "Setting should have been restored"
+
 
 class TestSettingTypes(TestCase):
     def test_settings_consistently_coerced_to_list(self):