Add initial test case for loading backers

ai_blocker/tests.py

@@ -1,3 +1,10 @@
 from django.test import TestCase
 
+from ai_blocker.ualist_backers import ConfigBackedUAList
+from middleware import load_backing_class
+
 # Create your tests here.
+class BackerConfigTestCase(TestCase):
+    def test_config_produces_object(self):
+        obj = load_backing_class("ai_blocker.ualist_backers.ConfigBackedUAList")
+        self.assertIs(obj, ConfigBackedUAList)