Add a test to make sure the random policy function runs.

test/test_gc.py

@@ -1,6 +1,8 @@
 import unittest
 import time
 
+from playhouse.test_utils import assert_query_count
+
 from app import app, storage
 from initdb import setup_database_for_testing, finished_database_for_testing
 from data import model, database
@@ -189,6 +191,13 @@ class TestGarbageCollection(unittest.TestCase):
     self.assertIsNone(model.repository.find_repository_with_garbage(0))
 
 
+  def test_find_garbage_policy_functions(self):
+    with assert_query_count(1):
+      one_policy = model.repository.get_random_gc_policy()
+      all_policies = model.repository._get_gc_expiration_policies()
+    self.assertIn(one_policy, all_policies)
+
+
   def test_one_tag(self):
     """ Create a repository with a single tag, then remove that tag and verify that the repository
         is now empty. """