diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkDeviceServiceTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkDeviceServiceTest.java
index 26e5080..ecb8b0d 100644
--- a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkDeviceServiceTest.java
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkDeviceServiceTest.java
@@ -32,11 +32,11 @@
 import org.onosproject.incubator.store.virtual.impl.DistributedVirtualNetworkStore;
 import org.onosproject.net.DefaultPort;
 import org.onosproject.net.Device;
-import org.onosproject.net.DeviceId;
 import org.onosproject.net.MastershipRole;
 import org.onosproject.net.NetTestTools;
 import org.onosproject.net.Port;
 import org.onosproject.net.PortNumber;
+import org.onosproject.net.TestDeviceParams;
 import org.onosproject.net.device.DeviceService;
 import org.onosproject.store.service.TestStorageService;
 
@@ -48,11 +48,8 @@
 /**
  * Junit tests for VirtualNetworkDeviceService.
  */
-public class VirtualNetworkDeviceServiceTest {
+public class VirtualNetworkDeviceServiceTest extends TestDeviceParams {
     private final String tenantIdValue1 = "TENANT_ID1";
-    private final String deviceIdValue1 = "DEVICE_ID1";
-    private final String deviceIdValue2 = "DEVICE_ID2";
-    private final String deviceIdValue3 = "DEVICE_ID3";
 
     private VirtualNetworkManager manager;
     private DistributedVirtualNetworkStore virtualNetworkManagerStore;
@@ -88,8 +85,8 @@
     public void testGetDevices() {
         manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
         VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
-        VirtualDevice device1 = manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue1));
-        VirtualDevice device2 = manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue2));
+        VirtualDevice device1 = manager.createVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice device2 = manager.createVirtualDevice(virtualNetwork.id(), DID2);
 
         DeviceService deviceService = manager.get(virtualNetwork.id(), DeviceService.class);
 
@@ -106,15 +103,15 @@
 
         // test the getDevice() method
         assertEquals("The expect device did not match.", device1,
-                     deviceService.getDevice(DeviceId.deviceId(deviceIdValue1)));
+                     deviceService.getDevice(DID1));
         assertNotEquals("The expect device should not have matched.", device1,
-                        deviceService.getDevice(DeviceId.deviceId(deviceIdValue2)));
+                        deviceService.getDevice(DID2));
 
         // test the isAvailable() method
         assertTrue("The expect device availability did not match.",
-                   deviceService.isAvailable(DeviceId.deviceId(deviceIdValue1)));
+                   deviceService.isAvailable(DID1));
         assertFalse("The expect device availability did not match.",
-                    deviceService.isAvailable(DeviceId.deviceId(deviceIdValue3)));
+                    deviceService.isAvailable(DID3));
     }
 
     /**
@@ -163,8 +160,8 @@
     public void testGetDeviceType() {
         manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
         VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
-        manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue1));
-        manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue2));
+        manager.createVirtualDevice(virtualNetwork.id(), DID1);
+        manager.createVirtualDevice(virtualNetwork.id(), DID2);
 
         DeviceService deviceService = manager.get(virtualNetwork.id(), DeviceService.class);
 
@@ -203,7 +200,7 @@
 
         // test the getRole() method
         assertEquals("The expect device role did not match.", MastershipRole.MASTER,
-                     deviceService.getRole(DeviceId.deviceId(deviceIdValue1)));
+                     deviceService.getRole(DID1));
     }
 
     /**
@@ -226,9 +223,8 @@
     public void testGetPorts() {
         manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
         VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
-        VirtualDevice virtualDevice = manager.createVirtualDevice(virtualNetwork.id(),
-                                                                  DeviceId.deviceId(deviceIdValue1));
-        manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue2));
+        VirtualDevice virtualDevice = manager.createVirtualDevice(virtualNetwork.id(), DID1);
+        manager.createVirtualDevice(virtualNetwork.id(), DID2);
 
         DeviceService deviceService = manager.get(virtualNetwork.id(), DeviceService.class);
 
@@ -239,9 +235,9 @@
 
         // test the getPorts() method
         assertEquals("The port set size did not match.", 2,
-                     deviceService.getPorts(DeviceId.deviceId(deviceIdValue1)).size());
+                     deviceService.getPorts(DID1).size());
         assertEquals("The port set size did not match.", 0,
-                     deviceService.getPorts(DeviceId.deviceId(deviceIdValue2)).size());
+                     deviceService.getPorts(DID2).size());
     }
 
     /**
@@ -251,9 +247,8 @@
     public void testGetPort() {
         manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
         VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
-        VirtualDevice virtualDevice = manager.createVirtualDevice(virtualNetwork.id(),
-                                                                  DeviceId.deviceId(deviceIdValue1));
-        manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue2));
+        VirtualDevice virtualDevice = manager.createVirtualDevice(virtualNetwork.id(), DID1);
+        manager.createVirtualDevice(virtualNetwork.id(), DID2);
 
         DeviceService deviceService = manager.get(virtualNetwork.id(), DeviceService.class);
 
@@ -265,9 +260,9 @@
 
         // test the getPort() method
         assertEquals("The port did not match as expected.", virtualPort1,
-                     deviceService.getPort(DeviceId.deviceId(deviceIdValue1), PortNumber.portNumber(1)));
+                     deviceService.getPort(DID1, PortNumber.portNumber(1)));
         assertNotEquals("The port did not match as expected.", virtualPort1,
-                        deviceService.getPort(DeviceId.deviceId(deviceIdValue1), PortNumber.portNumber(3)));
+                        deviceService.getPort(DID1, PortNumber.portNumber(3)));
     }
 
     /**
@@ -290,15 +285,14 @@
     public void testGetPortStatistics() {
         manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
         VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
-        VirtualDevice virtualDevice = manager.createVirtualDevice(virtualNetwork.id(),
-                                                                  DeviceId.deviceId(deviceIdValue1));
-        manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue2));
+        VirtualDevice virtualDevice = manager.createVirtualDevice(virtualNetwork.id(), DID1);
+        manager.createVirtualDevice(virtualNetwork.id(), DID2);
 
         DeviceService deviceService = manager.get(virtualNetwork.id(), DeviceService.class);
 
         // test the getPortStatistics() method
         assertEquals("The port statistics set size did not match.", 0,
-                     deviceService.getPortStatistics(DeviceId.deviceId(deviceIdValue1)).size());
+                     deviceService.getPortStatistics(DID1).size());
     }
 
     /**
@@ -321,15 +315,14 @@
     public void testGetPortDeltaStatistics() {
         manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
         VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
-        VirtualDevice virtualDevice = manager.createVirtualDevice(virtualNetwork.id(),
-                                                                  DeviceId.deviceId(deviceIdValue1));
-        manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue2));
+        VirtualDevice virtualDevice = manager.createVirtualDevice(virtualNetwork.id(), DID1);
+        manager.createVirtualDevice(virtualNetwork.id(), DID2);
 
         DeviceService deviceService = manager.get(virtualNetwork.id(), DeviceService.class);
 
         // test the getPortDeltaStatistics() method
         assertEquals("The port delta statistics set size did not match.", 0,
-                     deviceService.getPortDeltaStatistics(DeviceId.deviceId(deviceIdValue1)).size());
+                     deviceService.getPortDeltaStatistics(DID1).size());
     }
 
     /**
diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkLinkServiceTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkLinkServiceTest.java
index 5143b8b..f056f7c 100644
--- a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkLinkServiceTest.java
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkLinkServiceTest.java
@@ -31,10 +31,10 @@
 import org.onosproject.incubator.net.virtual.VirtualNetwork;
 import org.onosproject.incubator.store.virtual.impl.DistributedVirtualNetworkStore;
 import org.onosproject.net.ConnectPoint;
-import org.onosproject.net.DeviceId;
 import org.onosproject.net.Link;
 import org.onosproject.net.NetTestTools;
 import org.onosproject.net.PortNumber;
+import org.onosproject.net.TestDeviceParams;
 import org.onosproject.net.link.LinkService;
 import org.onosproject.store.service.TestStorageService;
 
@@ -47,12 +47,9 @@
 /**
  * Junit tests for VirtualNetworkLinkService.
  */
-public class VirtualNetworkLinkServiceTest {
+public class VirtualNetworkLinkServiceTest extends TestDeviceParams {
 
     private final String tenantIdValue1 = "TENANT_ID1";
-    private final String deviceIdValue1 = "DEVICE_ID1";
-    private final String deviceIdValue2 = "DEVICE_ID2";
-    private final String deviceIdValue3 = "DEVICE_ID3";
 
     private VirtualNetworkManager manager;
     private DistributedVirtualNetworkStore virtualNetworkManagerStore;
@@ -92,9 +89,9 @@
         manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
         VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
         VirtualDevice srcVirtualDevice =
-                manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue1));
+                manager.createVirtualDevice(virtualNetwork.id(), DID1);
         VirtualDevice dstVirtualDevice =
-                manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue2));
+                manager.createVirtualDevice(virtualNetwork.id(), DID2);
         ConnectPoint src = new ConnectPoint(srcVirtualDevice.id(), PortNumber.portNumber(1));
         ConnectPoint dst = new ConnectPoint(dstVirtualDevice.id(), PortNumber.portNumber(2));
         VirtualLink link1 = manager.createVirtualLink(virtualNetwork.id(), src, dst);
@@ -134,27 +131,27 @@
 
         // test the getDeviceLinks() method
         assertEquals("The link set size did not match.", 2,
-                     linkService.getDeviceLinks(DeviceId.deviceId(deviceIdValue1)).size());
+                     linkService.getDeviceLinks(DID1).size());
         assertEquals("The link set size did not match.", 2,
-                     linkService.getDeviceLinks(DeviceId.deviceId(deviceIdValue2)).size());
+                     linkService.getDeviceLinks(DID2).size());
         assertEquals("The link set size did not match.", 0,
-                     linkService.getDeviceLinks(DeviceId.deviceId(deviceIdValue3)).size());
+                     linkService.getDeviceLinks(DID3).size());
 
         // test the getDeviceEgressLinks() method
         assertEquals("The link set size did not match.", 1,
-                     linkService.getDeviceEgressLinks(DeviceId.deviceId(deviceIdValue1)).size());
+                     linkService.getDeviceEgressLinks(DID1).size());
         assertEquals("The link set size did not match.", 1,
-                     linkService.getDeviceEgressLinks(DeviceId.deviceId(deviceIdValue2)).size());
+                     linkService.getDeviceEgressLinks(DID2).size());
         assertEquals("The link set size did not match.", 0,
-                     linkService.getDeviceEgressLinks(DeviceId.deviceId(deviceIdValue3)).size());
+                     linkService.getDeviceEgressLinks(DID3).size());
 
         // test the getDeviceIngressLinks() method
         assertEquals("The link set size did not match.", 1,
-                     linkService.getDeviceIngressLinks(DeviceId.deviceId(deviceIdValue1)).size());
+                     linkService.getDeviceIngressLinks(DID1).size());
         assertEquals("The link set size did not match.", 1,
-                     linkService.getDeviceIngressLinks(DeviceId.deviceId(deviceIdValue2)).size());
+                     linkService.getDeviceIngressLinks(DID2).size());
         assertEquals("The link set size did not match.", 0,
-                     linkService.getDeviceIngressLinks(DeviceId.deviceId(deviceIdValue3)).size());
+                     linkService.getDeviceIngressLinks(DID3).size());
 
         // test the getEgressLinks() method
         assertEquals("The link set size did not match.", 1,
@@ -182,9 +179,9 @@
         manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
         VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
         VirtualDevice srcVirtualDevice =
-                manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue1));
+                manager.createVirtualDevice(virtualNetwork.id(), DID1);
         VirtualDevice dstVirtualDevice =
-                manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue2));
+                manager.createVirtualDevice(virtualNetwork.id(), DID2);
         ConnectPoint src = new ConnectPoint(srcVirtualDevice.id(), PortNumber.portNumber(1));
         ConnectPoint dst = new ConnectPoint(dstVirtualDevice.id(), PortNumber.portNumber(2));
         manager.createVirtualLink(virtualNetwork.id(), src, dst);
@@ -205,9 +202,9 @@
         manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
         VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
         VirtualDevice srcVirtualDevice =
-                manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue1));
+                manager.createVirtualDevice(virtualNetwork.id(), DID1);
         VirtualDevice dstVirtualDevice =
-                manager.createVirtualDevice(virtualNetwork.id(), DeviceId.deviceId(deviceIdValue2));
+                manager.createVirtualDevice(virtualNetwork.id(), DID2);
         ConnectPoint src = new ConnectPoint(srcVirtualDevice.id(), PortNumber.portNumber(1));
         ConnectPoint dst = new ConnectPoint(dstVirtualDevice.id(), PortNumber.portNumber(2));
         manager.createVirtualLink(virtualNetwork.id(), src, dst);
diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkTopologyServiceTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkTopologyServiceTest.java
new file mode 100644
index 0000000..d199723
--- /dev/null
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkTopologyServiceTest.java
@@ -0,0 +1,599 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * 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.
+ */
+
+package org.onosproject.incubator.net.virtual.impl;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.onlab.junit.TestUtils;
+import org.onosproject.common.event.impl.TestEventDispatcher;
+import org.onosproject.core.CoreService;
+import org.onosproject.core.CoreServiceAdapter;
+import org.onosproject.core.IdGenerator;
+import org.onosproject.incubator.net.virtual.NetworkId;
+import org.onosproject.incubator.net.virtual.TenantId;
+import org.onosproject.incubator.net.virtual.VirtualDevice;
+import org.onosproject.incubator.net.virtual.VirtualLink;
+import org.onosproject.incubator.net.virtual.VirtualNetwork;
+import org.onosproject.incubator.store.virtual.impl.DistributedVirtualNetworkStore;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.DisjointPath;
+import org.onosproject.net.Link;
+import org.onosproject.net.NetTestTools;
+import org.onosproject.net.Path;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.TestDeviceParams;
+import org.onosproject.net.topology.LinkWeight;
+import org.onosproject.net.topology.Topology;
+import org.onosproject.net.topology.TopologyCluster;
+import org.onosproject.net.topology.TopologyService;
+import org.onosproject.store.service.TestStorageService;
+
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicLong;
+
+import static junit.framework.TestCase.assertTrue;
+import static org.junit.Assert.*;
+
+/**
+ * Junit tests for VirtualNetworkTopologyService.
+ */
+public class VirtualNetworkTopologyServiceTest extends TestDeviceParams {
+
+    private final String tenantIdValue1 = "TENANT_ID1";
+
+    private VirtualNetworkManager manager;
+    private DistributedVirtualNetworkStore virtualNetworkManagerStore;
+    private CoreService coreService;
+
+    @Before
+    public void setUp() throws Exception {
+        virtualNetworkManagerStore = new DistributedVirtualNetworkStore();
+
+        coreService = new VirtualNetworkTopologyServiceTest.TestCoreService();
+        virtualNetworkManagerStore.setCoreService(coreService);
+        TestUtils.setField(coreService, "coreService", new VirtualNetworkTopologyServiceTest.TestCoreService());
+        TestUtils.setField(virtualNetworkManagerStore, "storageService", new TestStorageService());
+        virtualNetworkManagerStore.activate();
+
+        manager = new VirtualNetworkManager();
+        manager.store = virtualNetworkManagerStore;
+        NetTestTools.injectEventDispatcher(manager, new TestEventDispatcher());
+        manager.activate();
+    }
+
+    @After
+    public void tearDown() {
+        virtualNetworkManagerStore.deactivate();
+        manager.deactivate();
+        NetTestTools.injectEventDispatcher(manager, null);
+    }
+
+    /**
+     * Method to create the virtual network for further testing.
+     *
+     * @return virtual network
+     */
+    private VirtualNetwork setupVirtualNetworkTopology() {
+        manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
+        VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
+        VirtualDevice virtualDevice1 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice virtualDevice2 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID2);
+        VirtualDevice virtualDevice3 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID3);
+        VirtualDevice virtualDevice4 =
+                manager.createVirtualDevice(virtualNetwork.id(), DID4);
+
+        ConnectPoint cp1 = new ConnectPoint(virtualDevice1.id(), PortNumber.portNumber(1));
+        ConnectPoint cp2 = new ConnectPoint(virtualDevice1.id(), PortNumber.portNumber(2));
+        ConnectPoint cp3 = new ConnectPoint(virtualDevice2.id(), PortNumber.portNumber(3));
+        ConnectPoint cp4 = new ConnectPoint(virtualDevice2.id(), PortNumber.portNumber(4));
+        ConnectPoint cp5 = new ConnectPoint(virtualDevice3.id(), PortNumber.portNumber(5));
+        ConnectPoint cp6 = new ConnectPoint(virtualDevice3.id(), PortNumber.portNumber(6));
+        VirtualLink link1 = manager.createVirtualLink(virtualNetwork.id(), cp1, cp3);
+        virtualNetworkManagerStore.updateLink(link1, link1.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link2 = manager.createVirtualLink(virtualNetwork.id(), cp3, cp1);
+        virtualNetworkManagerStore.updateLink(link2, link2.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link3 = manager.createVirtualLink(virtualNetwork.id(), cp4, cp5);
+        virtualNetworkManagerStore.updateLink(link3, link3.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link4 = manager.createVirtualLink(virtualNetwork.id(), cp5, cp4);
+        virtualNetworkManagerStore.updateLink(link4, link4.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link5 = manager.createVirtualLink(virtualNetwork.id(), cp2, cp6);
+        virtualNetworkManagerStore.updateLink(link5, link5.tunnelId(), Link.State.ACTIVE);
+        VirtualLink link6 = manager.createVirtualLink(virtualNetwork.id(), cp6, cp2);
+        virtualNetworkManagerStore.updateLink(link6, link6.tunnelId(), Link.State.ACTIVE);
+
+        return virtualNetwork;
+    }
+
+    /**
+     * Tests the currentTopology() method.
+     */
+    @Test
+    public void testCurrentTopology() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+        assertNotNull("The topology should not be null.", topology);
+    }
+
+    /**
+     * Test isLatest() method using a null topology.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testIsLatestByNullTopology() {
+        manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
+        VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+
+        // test the isLatest() method with a null topology.
+        topologyService.isLatest(null);
+    }
+
+    /**
+     * Test isLatest() method.
+     */
+    @Test
+    public void testIsLatest() {
+        manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
+        VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        // test the isLatest() method.
+        assertTrue("This should be latest topology", topologyService.isLatest(topology));
+
+        VirtualDevice srcVirtualDevice =
+                manager.createVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice =
+                manager.createVirtualDevice(virtualNetwork.id(), DID2);
+
+        // test the isLatest() method where a new device has been added to the current topology.
+        assertFalse("This should not be latest topology", topologyService.isLatest(topology));
+
+        topology = topologyService.currentTopology();
+        ConnectPoint src = new ConnectPoint(srcVirtualDevice.id(), PortNumber.portNumber(1));
+        ConnectPoint dst = new ConnectPoint(dstVirtualDevice.id(), PortNumber.portNumber(2));
+        VirtualLink link1 = manager.createVirtualLink(virtualNetwork.id(), src, dst);
+
+        // test the isLatest() method where a new link has been added to the current topology.
+        assertFalse("This should not be latest topology", topologyService.isLatest(topology));
+    }
+
+    /**
+     * Test getGraph() method.
+     */
+    @Test
+    public void testGetGraph() {
+        manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
+        VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        // test the getGraph() method.
+        assertNotNull("The graph should not be null.", topologyService.getGraph(topology));
+    }
+
+    /**
+     * Test getClusters() method.
+     */
+    @Test
+    public void testGetClusters() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+
+        Topology topology = topologyService.currentTopology();
+
+        // test the getClusters() method.
+        assertNotNull("The clusters should not be null.", topologyService.getClusters(topology));
+        assertEquals("The clusters size did not match.", 2, topologyService.getClusters(topology).size());
+    }
+
+    /**
+     * Test getCluster() method using a null cluster identifier.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testGetClusterUsingNullClusterId() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        Set<TopologyCluster> clusters = topologyService.getClusters(topology);
+        TopologyCluster cluster = clusters.stream().findFirst().get();
+
+        // test the getCluster() method with a null cluster identifier
+        TopologyCluster cluster1 = topologyService.getCluster(topology, null);
+    }
+
+    /**
+     * Test getCluster() method.
+     */
+    @Test
+    public void testGetCluster() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        Set<TopologyCluster> clusters = topologyService.getClusters(topology);
+        assertNotNull("The clusters should not be null.", clusters);
+        assertEquals("The clusters size did not match.", 2, clusters.size());
+
+        // test the getCluster() method.
+        TopologyCluster cluster = clusters.stream().findFirst().get();
+        assertNotNull("The cluster should not be null.", cluster);
+        TopologyCluster cluster1 = topologyService.getCluster(topology, cluster.id());
+        assertNotNull("The cluster should not be null.", cluster1);
+        assertEquals("The cluster ID did not match.", cluster.id(), cluster1.id());
+    }
+
+    /**
+     * Test getClusterDevices() methods with a null cluster.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testGetClusterDevicesUsingNullCluster() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+        Set<TopologyCluster> clusters = topologyService.getClusters(topology);
+
+        // test the getClusterDevices() method using a null cluster.
+        Object[] objects = clusters.stream().toArray();
+        assertNotNull("The cluster should not be null.", objects);
+        Set<DeviceId> clusterDevices = topologyService.getClusterDevices(topology, null);
+    }
+
+    /**
+     * Test getClusterLinks() methods with a null cluster.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testGetClusterLinksUsingNullCluster() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+        Set<TopologyCluster> clusters = topologyService.getClusters(topology);
+
+        // test the getClusterLinks() method using a null cluster.
+        Object[] objects = clusters.stream().toArray();
+        assertNotNull("The cluster should not be null.", objects);
+        Set<Link> clusterLinks = topologyService.getClusterLinks(topology, null);
+    }
+
+    /**
+     * Test getClusterDevices() and getClusterLinks() methods.
+     */
+    @Test
+    public void testGetClusterDevicesLinks() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        Set<TopologyCluster> clusters = topologyService.getClusters(topology);
+        assertNotNull("The clusters should not be null.", clusters);
+        assertEquals("The clusters size did not match.", 2, clusters.size());
+
+        // test the getClusterDevices() method.
+        Object[] objects = clusters.stream().toArray();
+        assertNotNull("The cluster should not be null.", objects);
+        Set<DeviceId> clusterDevices = topologyService.getClusterDevices(topology, (TopologyCluster) objects[0]);
+        assertNotNull("The devices should not be null.", clusterDevices);
+        assertEquals("The devices size did not match.", 3, clusterDevices.size());
+        Set<DeviceId> clusterDevices1 = topologyService.getClusterDevices(topology, (TopologyCluster) objects[1]);
+        assertNotNull("The devices should not be null.", clusterDevices1);
+        assertEquals("The devices size did not match.", 1, clusterDevices1.size());
+
+        // test the getClusterLinks() method.
+        Set<Link> clusterLinks = topologyService.getClusterLinks(topology, (TopologyCluster) objects[0]);
+        assertNotNull("The links should not be null.", clusterLinks);
+        assertEquals("The links size did not match.", 6, clusterLinks.size());
+        Set<Link> clusterLinks1 = topologyService.getClusterLinks(topology, (TopologyCluster) objects[1]);
+        assertNotNull("The links should not be null.", clusterLinks1);
+        assertEquals("The links size did not match.", 0, clusterLinks1.size());
+    }
+
+    /**
+     * Test getPaths() method using a null src device identifier.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testGetPathsUsingNullSrcDeviceId() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID2);
+
+        // test the getPaths() method using a null src device identifier.
+        Set<Path> paths = topologyService.getPaths(topology, null, dstVirtualDevice.id());
+    }
+
+    /**
+     * Test getPaths() method using a null dst device identifier.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testGetPathsUsingNullDstDeviceId() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID2);
+
+        // test the getPaths() method using a null dst device identifier.
+        Set<Path> paths = topologyService.getPaths(topology, srcVirtualDevice.id(), null);
+    }
+
+    /**
+     * Test getPaths() method using a null weight.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testGetPathsUsingNullWeight() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID2);
+
+        // test the getPaths() method using a null weight.
+        Set<Path> paths = topologyService.getPaths(topology, srcVirtualDevice.id(), dstVirtualDevice.id(), null);
+    }
+
+    /**
+     * Test getPaths() and getPaths() by weight methods.
+     */
+    @Test
+    public void testGetPaths() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID2);
+
+        // test the getPaths() method.
+        Set<Path> paths = topologyService.getPaths(topology, srcVirtualDevice.id(), dstVirtualDevice.id());
+        assertNotNull("The paths should not be null.", paths);
+        assertEquals("The paths size did not match.", 1, paths.size());
+
+        // test the getPaths() by weight method.
+        LinkWeight weight = edge -> 1.0;
+        Set<Path> paths1 = topologyService.getPaths(topology, srcVirtualDevice.id(), dstVirtualDevice.id(), weight);
+        assertNotNull("The paths should not be null.", paths1);
+        assertEquals("The paths size did not match.", 1, paths1.size());
+        Path path = paths1.iterator().next();
+        assertEquals("wrong path length", 1, path.links().size());
+        assertEquals("wrong path cost", 1.0, path.cost(), 0.01);
+    }
+
+    /**
+     * Test getDisjointPaths() methods using a null src device identifier.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testGetDisjointPathsUsingNullSrcDeviceId() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID2);
+
+        // test the getDisjointPaths() method using a null src device identifier.
+        Set<DisjointPath> paths = topologyService.getDisjointPaths(topology, null, dstVirtualDevice.id());
+    }
+
+    /**
+     * Test getDisjointPaths() methods using a null dst device identifier.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testGetDisjointPathsUsingNullDstDeviceId() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID2);
+
+        // test the getDisjointPaths() method using a null dst device identifier.
+        Set<DisjointPath> paths = topologyService.getDisjointPaths(topology, srcVirtualDevice.id(), null);
+    }
+
+    /**
+     * Test getDisjointPaths() methods using a null weight.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testGetDisjointPathsUsingNullWeight() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID2);
+
+        // test the getDisjointPaths() method using a null weight.
+        Set<DisjointPath> paths = topologyService.getDisjointPaths(topology, srcVirtualDevice.id(),
+                                                                   dstVirtualDevice.id(), (LinkWeight) null);
+    }
+
+    /**
+     * Test getDisjointPaths() methods using a null risk profile.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testGetDisjointPathsUsingNullRiskProfile() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID2);
+
+        // test the getDisjointPaths() method using a null risk profile.
+        Set<DisjointPath> paths = topologyService.getDisjointPaths(topology, srcVirtualDevice.id(),
+                                                                   dstVirtualDevice.id(), (Map<Link, Object>) null);
+    }
+
+    /**
+     * Test getDisjointPaths() methods.
+     */
+    @Test
+    public void testGetDisjointPaths() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID2);
+
+        // test the getDisjointPaths() method.
+        Set<DisjointPath> paths = topologyService.getDisjointPaths(topology, srcVirtualDevice.id(),
+                                                                   dstVirtualDevice.id());
+        assertNotNull("The paths should not be null.", paths);
+        assertEquals("The paths size did not match.", 1, paths.size());
+
+        // test the getDisjointPaths() method using a weight.
+        LinkWeight weight = edge -> 1.0;
+        Set<DisjointPath> paths1 = topologyService.getDisjointPaths(topology, srcVirtualDevice.id(),
+                                                                    dstVirtualDevice.id(), weight);
+        assertNotNull("The paths should not be null.", paths1);
+        assertEquals("The paths size did not match.", 1, paths1.size());
+    }
+
+    /**
+     * Test isInfrastructure() method using a null connect point.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testIsInfrastructureUsingNullConnectPoint() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        // test the isInfrastructure() method using a null connect point.
+        Boolean isInfrastructure = topologyService.isInfrastructure(topology, null);
+    }
+
+    /**
+     * Test isInfrastructure() method.
+     */
+    @Test
+    public void testIsInfrastructure() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        VirtualDevice dstVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID4);
+        ConnectPoint cp1 = new ConnectPoint(srcVirtualDevice.id(), PortNumber.portNumber(1));
+        ConnectPoint cp2 = new ConnectPoint(dstVirtualDevice.id(), PortNumber.portNumber(2));
+
+        // test the isInfrastructure() method.
+        Boolean isInfrastructure = topologyService.isInfrastructure(topology, cp1);
+        assertTrue("The connect point should be infrastructure.", isInfrastructure);
+
+        isInfrastructure = topologyService.isInfrastructure(topology, cp2);
+        assertFalse("The connect point should not be infrastructure.", isInfrastructure);
+    }
+
+    /**
+     * Test isBroadcastPoint() method using a null connect point.
+     */
+    @Test(expected = NullPointerException.class)
+    public void testIsBroadcastUsingNullConnectPoint() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        // test the isInfrastructure() method using a null connect point.
+        Boolean isInfrastructure = topologyService.isBroadcastPoint(topology, null);
+    }
+
+    /**
+     * Test isBroadcastPoint() method.
+     */
+    @Test
+    public void testIsBroadcastPoint() {
+        VirtualNetwork virtualNetwork = setupVirtualNetworkTopology();
+
+        TopologyService topologyService = manager.get(virtualNetwork.id(), TopologyService.class);
+        Topology topology = topologyService.currentTopology();
+
+        VirtualDevice srcVirtualDevice = getVirtualDevice(virtualNetwork.id(), DID1);
+        ConnectPoint cp = new ConnectPoint(srcVirtualDevice.id(), PortNumber.portNumber(1));
+
+        // test the isBroadcastPoint() method.
+        Boolean isBroadcastPoint = topologyService.isBroadcastPoint(topology, cp);
+        assertTrue("The connect point should be a broadcast point.", isBroadcastPoint);
+    }
+
+    /**
+     * Return the virtual device matching the device identifier.
+     *
+     * @param networkId virtual network identifier
+     * @param deviceId  device identifier
+     * @return virtual device
+     */
+    private VirtualDevice getVirtualDevice(NetworkId networkId, DeviceId deviceId) {
+        Optional<VirtualDevice> foundDevice = manager.getVirtualDevices(networkId)
+                .stream()
+                .filter(device -> deviceId.equals(device.id()))
+                .findFirst();
+        if (foundDevice.isPresent()) {
+            return foundDevice.get();
+        }
+        return null;
+    }
+
+    /**
+     * Core service test class.
+     */
+    private class TestCoreService extends CoreServiceAdapter {
+
+        @Override
+        public IdGenerator getIdGenerator(String topic) {
+            return new IdGenerator() {
+                private AtomicLong counter = new AtomicLong(0);
+
+                @Override
+                public long getNewId() {
+                    return counter.getAndIncrement();
+                }
+            };
+        }
+    }
+}