diff --git a/keystone/tests/test_backend.py b/keystone/tests/test_backend.py
index babfed7bc..de2c7ddef 100644
--- a/keystone/tests/test_backend.py
+++ b/keystone/tests/test_backend.py
@@ -22,7 +22,6 @@ from keystoneclient.common import cms
 import six
 from testtools import matchers
 
-from keystone.catalog import core
 from keystone.common import driver_hints
 from keystone import config
 from keystone import exception
@@ -3639,26 +3638,6 @@ class TrustTests(object):
         self.assertIsNone(self.trust_api.get_trust(trust_data['id']))
 
 
-class CommonHelperTests(tests.TestCase):
-    def test_format_helper_raises_malformed_on_missing_key(self):
-        self.assertRaises(exception.MalformedEndpoint,
-                          core.format_url,
-                          "http://%(foo)s/%(bar)s",
-                          {"foo": "1"})
-
-    def test_format_helper_raises_malformed_on_wrong_type(self):
-        self.assertRaises(exception.MalformedEndpoint,
-                          core.format_url,
-                          "http://%foo%s",
-                          {"foo": "1"})
-
-    def test_format_helper_raises_malformed_on_incomplete_format(self):
-        self.assertRaises(exception.MalformedEndpoint,
-                          core.format_url,
-                          "http://%(foo)",
-                          {"foo": "1"})
-
-
 class CatalogTests(object):
     def test_region_crud(self):
         # create
diff --git a/keystone/tests/unit/catalog/__init__.py b/keystone/tests/unit/catalog/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/keystone/tests/unit/catalog/test_core.py b/keystone/tests/unit/catalog/test_core.py
new file mode 100644
index 000000000..37d73e61b
--- /dev/null
+++ b/keystone/tests/unit/catalog/test_core.py
@@ -0,0 +1,54 @@
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import testtools
+
+from keystone.catalog import core
+from keystone import exception
+
+
+class FormatUrlTests(testtools.TestCase):
+
+    def test_successful_formatting(self):
+        url_template = 'http://%(host)s:%(port)d/%(part1)s/%(part2)s'
+        values = {'host': 'server', 'port': 9090, 'part1': 'A', 'part2': 'B'}
+        actual_url = core.format_url(url_template, values)
+
+        expected_url = 'http://server:9090/A/B'
+        self.assertEqual(actual_url, expected_url)
+
+    def test_raises_malformed_on_missing_key(self):
+        self.assertRaises(exception.MalformedEndpoint,
+                          core.format_url,
+                          "http://%(foo)s/%(bar)s",
+                          {"foo": "1"})
+
+    def test_raises_malformed_on_wrong_type(self):
+        self.assertRaises(exception.MalformedEndpoint,
+                          core.format_url,
+                          "http://%foo%s",
+                          {"foo": "1"})
+
+    def test_raises_malformed_on_incomplete_format(self):
+        self.assertRaises(exception.MalformedEndpoint,
+                          core.format_url,
+                          "http://%(foo)",
+                          {"foo": "1"})
+
+    def test_formatting_a_non_string(self):
+        def _test(url_template):
+            expected_url = None
+            actual_url = core.format_url(url_template, {})
+            self.assertEqual(actual_url, expected_url)
+
+        _test(None)
+        _test(object())