diff --git a/referral/tests/models_tests.py b/referral/tests/models_tests.py
index <HASH>..<HASH> 100644
--- a/referral/tests/models_tests.py
+++ b/referral/tests/models_tests.py
@@ -8,3 +8,7 @@ class CampaignTestCase(TestCase):
         obj = CampaignFactory()
         self.assertTrue(obj.pk)
 
+    def test_count_users(self):
+        obj = CampaignFactory()
+        self.assertEqual(obj.count_users(),0)
+
add testcase for count_users