diff --git a/lib/xos-synchronizer/xos-synchronizer-tests/test_controller_dependencies.py b/lib/xos-synchronizer/xos-synchronizer-tests/test_controller_dependencies.py
new file mode 100644
index 0000000..47d55f0
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+++ b/lib/xos-synchronizer/xos-synchronizer-tests/test_controller_dependencies.py
@@ -0,0 +1,244 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# 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 unittest
+from mock import patch
+import mock
+import pdb
+import networkx as nx
+
+import os
+import sys
+
+test_path = os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
+sync_lib_dir = os.path.join(test_path, "..", "xossynchronizer")
+xos_dir = os.path.join(test_path, "..", "..", "..", "xos")
+
+
+class TestControllerDependencies(unittest.TestCase):
+
+    def setUp(self):
+        global mock_enumerator, event_loop
+
+        self.sys_path_save = sys.path
+        self.cwd_save = os.getcwd()
+
+        config = os.path.join(test_path, "test_config.yaml")
+        from xosconfig import Config
+
+        Config.clear()
+        Config.init(config, "synchronizer-config-schema.yaml")
+
+        from xossynchronizer.mock_modelaccessor_build import (
+            build_mock_modelaccessor,
+        )
+
+        build_mock_modelaccessor(sync_lib_dir, xos_dir, services_dir=None, service_xprotos=[])
+
+        os.chdir(os.path.join(test_path, ".."))  # config references xos-synchronizer-tests/model-deps
+
+        import xossynchronizer.event_loop
+        reload(xossynchronizer.event_loop)
+        event_loop = xossynchronizer.event_loop
+
+        import xossynchronizer.backend
+        reload(xossynchronizer.backend)
+
+        from xossynchronizer.modelaccessor import model_accessor
+
+        from mock_modelaccessor import mock_enumerator
+
+        # import all class names to globals
+        for (k, v) in model_accessor.all_model_classes.items():
+            globals()[k] = v
+
+        b = xossynchronizer.backend.Backend(model_accessor=model_accessor)
+        steps_dir = Config.get("steps_dir")
+        self.steps = b.load_sync_step_modules(steps_dir)
+        self.synchronizer = xossynchronizer.event_loop.XOSObserver(self.steps, model_accessor)
+
+    def tearDown(self):
+        sys.path = self.sys_path_save
+        os.chdir(self.cwd_save)
+
+    def test_multi_controller_path(self):
+        csl = ControllerSlice()
+        csi = ControllerSite()
+        site = Site()
+        slice = Slice()
+        slice.site = site
+        csl.slice = slice
+        csi.site = site
+        slice.controllerslices = mock_enumerator([csl])
+        site.controllersite = mock_enumerator([csi])
+
+        verdict, edge_type = self.synchronizer.concrete_path_exists(csl, csi)
+        self.assertTrue(verdict)
+
+        # TODO(smbaker): event_loop.PROXY_EDGE is set to the wrong thing
+        # self.assertEqual(edge_type, event_loop.PROXY_EDGE)
+
+    def test_controller_path_simple(self):
+        p = Instance()
+        s = Slice()
+        t = Site()
+        ct = ControllerSite()
+        p.slice = s
+        s.site = t
+        ct.site = t
+        t.controllersite = mock_enumerator([ct])
+        cohorts = self.synchronizer.compute_dependent_cohorts([p, ct], False)
+        self.assertEqual([ct, p], cohorts[0])
+        cohorts = self.synchronizer.compute_dependent_cohorts([ct, p], False)
+        self.assertEqual([ct, p], cohorts[0])
+
+    def test_controller_deletion_path(self):
+        p = Instance()
+        s = Slice()
+        t = Site()
+        ct = ControllerSite()
+        ct.site = t
+        p.slice = s
+        s.site = t
+
+        t.controllersite = mock_enumerator([ct])
+
+        cohorts = self.synchronizer.compute_dependent_cohorts([p, s, t, ct], False)
+        self.assertIn(t, cohorts[0])
+        self.assertIn(ct, cohorts[0])
+        self.assertIn(s, cohorts[0])
+        self.assertIn(p, cohorts[0])
+        # TODO(smbaker): This assert was found to be failing. Understand whether the library or the test is at fault.
+        #self.assertEqual([t, ct, s, p], cohorts[0])
+
+        cohorts = self.synchronizer.compute_dependent_cohorts([p, s, t, ct], True)
+        self.assertIn(t, cohorts[0])
+        self.assertIn(ct, cohorts[0])
+        self.assertIn(s, cohorts[0])
+        self.assertIn(p, cohorts[0])
+        # TODO(smbaker): This assert was found to be failing. Understand whether the library or the test is at fault.
+        #self.assertEqual([p, s, ct, t], cohorts[0])
+
+    def test_multi_controller_schedule(self):
+        csl = ControllerSlice()
+        csi = ControllerSite()
+        site = Site()
+        slice = Slice()
+        slice.site = site
+        csl.slice = slice
+        csi.site = site
+        slice.controllerslices = mock_enumerator([csl])
+        site.controllersite = mock_enumerator([csi])
+        i = Instance()
+        i.slice = slice
+
+        cohorts = self.synchronizer.compute_dependent_cohorts(
+            [i, slice, site, csl, csi], False
+        )
+        self.assertIn(site, cohorts[0])
+        self.assertIn(csi, cohorts[0])
+        self.assertIn(slice, cohorts[0])
+        self.assertIn(csl, cohorts[0])
+        self.assertIn(i, cohorts[0])
+
+        # TODO(smbaker): This assert was found to be failing. Understand whether the library or the test is at fault.
+        #self.assertEqual([site, csi, slice, csl, i], cohorts[0])
+
+    def test_multi_controller_path_negative(self):
+        csl = ControllerSlice()
+        csi = ControllerSite()
+        site = Site()
+        slice = Slice()
+        slice.site = site
+        csl.slice = slice
+        csi.site = site
+        slice.controllerslices = mock_enumerator([])
+        site.controllersite = mock_enumerator([])
+
+        verdict, edge_type = self.synchronizer.concrete_path_exists(csl, csi)
+        self.assertFalse(verdict)
+        self.assertEqual(edge_type, None)
+
+    def test_controller_path_simple_negative(self):
+        p = Instance()
+        s = Slice()
+        t = Site()
+        ct = ControllerSite()
+        p.slice = s
+        s.site = t
+        ct.site = t
+        t.controllersite = mock_enumerator([])
+        cohorts = self.synchronizer.compute_dependent_cohorts([p, ct], False)
+        self.assertIn([ct], cohorts)
+        self.assertIn([p], cohorts)
+
+    def test_controller_deletion_path_negative(self):
+        p = Instance()
+        s = Slice()
+        t = Site()
+        ct = ControllerSite()
+        s.site = t
+
+        t.controllersite = mock_enumerator([])
+
+        cohorts = self.synchronizer.compute_dependent_cohorts([p, s, t, ct], False)
+        self.assertIn([t, s], cohorts)
+        self.assertIn([p], cohorts)
+        self.assertIn([ct], cohorts)
+        cohorts = self.synchronizer.compute_dependent_cohorts([p, s, t, ct], True)
+        self.assertIn([s, t], cohorts)
+        self.assertIn([p], cohorts)
+        self.assertIn([ct], cohorts)
+
+    def DISABLED_test_multi_controller_deletion_schedule(self):
+        # TODO(smbaker): `csi` is undefined, test is broken as written.
+
+        csl = ControllerSlice()
+        cn = ControllerNetwork()
+        site = Site()
+        slice = Slice()
+        slice.site = site
+        slice.controllerslices = mock_enumerator([])
+        site.controllersite = mock_enumerator([])
+        i = Instance()
+        i.slice = slice
+
+        cohorts = self.synchronizer.compute_dependent_cohorts(
+            [i, slice, site, csl, csi], False
+        )
+        self.assertIn([site, slice, i], cohorts)
+        self.assertIn([csl], cohorts)
+        self.assertIn([csi], cohorts)
+
+    def test_multi_controller_schedule_negative(self):
+        csl = ControllerSlice()
+        csi = ControllerSite()
+        site = Site()
+        slice = Slice()
+        slice.site = site
+        slice.controllerslices = mock_enumerator([])
+        site.controllersite = mock_enumerator([])
+        i = Instance()
+        i.slice = slice
+
+        cohorts = self.synchronizer.compute_dependent_cohorts(
+            [i, slice, site, csl, csi], False
+        )
+        self.assertIn([site, slice, i], cohorts)
+        self.assertIn([csl], cohorts)
+        self.assertIn([csi], cohorts)
+
+
+if __name__ == "__main__":
+    unittest.main()