diff --git a/incubator/protobuf/services/nb/src/test/java/org/onosproject/incubator/protobuf/services/nb/GrpcNbMastershipServiceTest.java b/incubator/protobuf/services/nb/src/test/java/org/onosproject/incubator/protobuf/services/nb/GrpcNbMastershipServiceTest.java
new file mode 100644
index 0000000..dd7abfc
--- /dev/null
+++ b/incubator/protobuf/services/nb/src/test/java/org/onosproject/incubator/protobuf/services/nb/GrpcNbMastershipServiceTest.java
@@ -0,0 +1,246 @@
+/*
+ * 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.
+ */
+package org.onosproject.incubator.protobuf.services.nb;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Maps;
+import io.grpc.BindableService;
+import io.grpc.ManagedChannel;
+import io.grpc.inprocess.InProcessChannelBuilder;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.onosproject.cluster.NodeId;
+import org.onosproject.cluster.RoleInfo;
+import org.onosproject.grpc.nb.mastership.MastershipServiceGrpc;
+import org.onosproject.grpc.nb.mastership.MastershipServiceNb.getLocalRoleReply;
+import org.onosproject.grpc.nb.mastership.MastershipServiceNb.getLocalRoleRequest;
+import org.onosproject.grpc.nb.mastership.MastershipServiceNb.getMasterForReply;
+import org.onosproject.grpc.nb.mastership.MastershipServiceNb.getMasterForRequest;
+import org.onosproject.grpc.nb.mastership.MastershipServiceNb.getNodesForReply;
+import org.onosproject.grpc.nb.mastership.MastershipServiceNb.getNodesForRequest;
+import org.onosproject.grpc.nb.mastership.MastershipServiceNb.requestRoleForSyncReply;
+import org.onosproject.grpc.nb.mastership.MastershipServiceNb.requestRoleForSyncRequest;
+import org.onosproject.incubator.protobuf.models.cluster.NodeIdProtoTranslator;
+import org.onosproject.incubator.protobuf.models.net.MastershipRoleProtoTranslator;
+import org.onosproject.mastership.MastershipListener;
+import org.onosproject.mastership.MastershipService;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.MastershipRole;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Unit tests for mastership gRPC NB service.
+ */
+public class GrpcNbMastershipServiceTest {
+
+    private static InProcessServer<BindableService> inprocessServer;
+    private static MastershipServiceGrpc.MastershipServiceBlockingStub blockingStub;
+    private static ManagedChannel channel;
+
+    private final MastershipService mastershipService = new MockMastershipService();
+
+    private Map<DeviceId, MastershipRole> mastershipMap = Maps.newHashMap();
+    private Map<DeviceId, NodeId> nodeIdMap = Maps.newHashMap();
+    private Map<DeviceId, RoleInfo> roleInfoMap = Maps.newHashMap();
+
+    private static final String DEVICE_ID_1 = "1";
+    private static final String DEVICE_ID_2 = "2";
+    private static final String DEVICE_ID_3 = "3";
+
+    private DeviceId did1 = DeviceId.deviceId(DEVICE_ID_1);
+    private DeviceId did2 = DeviceId.deviceId(DEVICE_ID_2);
+    private DeviceId did3 = DeviceId.deviceId(DEVICE_ID_3);
+
+    private NodeId nid1 = NodeId.nodeId("1");
+    private NodeId nid2 = NodeId.nodeId("2");
+    private NodeId nid3 = NodeId.nodeId("3");
+
+    /**
+     * Initializes the test environment.
+     */
+    @Before
+    public void setUp() throws IllegalAccessException, IOException, InstantiationException {
+        GrpcNbMastershipService grpcMastershipService = new GrpcNbMastershipService();
+        grpcMastershipService.mastershipService = mastershipService;
+        inprocessServer = grpcMastershipService.registerInProcessServer();
+        inprocessServer.start();
+
+        channel = InProcessChannelBuilder.forName("test").directExecutor()
+                .usePlaintext(true).build();
+
+        blockingStub = MastershipServiceGrpc.newBlockingStub(channel);
+
+        initMastershipMap();
+        initNodeIdMap();
+        initRoleInfoMap();
+    }
+
+    /**
+     * Finalizes the test setup.
+     */
+    @After
+    public void tearDown() {
+        channel.shutdownNow();
+        inprocessServer.stop();
+    }
+
+    private void initMastershipMap() {
+        mastershipMap.put(did1, MastershipRole.MASTER);
+        mastershipMap.put(did2, MastershipRole.STANDBY);
+        mastershipMap.put(did3, MastershipRole.NONE);
+    }
+
+    private void initNodeIdMap() {
+        nodeIdMap.put(did1, nid1);
+        nodeIdMap.put(did2, nid2);
+        nodeIdMap.put(did3, nid3);
+    }
+
+    private void initRoleInfoMap() {
+        RoleInfo roleInfo1 = new RoleInfo(nid1, ImmutableList.of(nid2, nid3));
+        RoleInfo roleInfo2 = new RoleInfo(nid2, ImmutableList.of(nid1, nid3));
+        RoleInfo roleInfo3 = new RoleInfo(nid3, ImmutableList.of(nid2, nid3));
+        roleInfoMap.put(did1, roleInfo1);
+        roleInfoMap.put(did2, roleInfo2);
+        roleInfoMap.put(did3, roleInfo3);
+    }
+
+    /**
+     * Tests the invocation result of getLocalRole method.
+     *
+     * @throws InterruptedException
+     */
+    @Test
+    public void testGetLocalRole() throws InterruptedException {
+        getLocalRoleRequest request = getLocalRoleRequest.newBuilder()
+                .setDeviceId(DEVICE_ID_1)
+                .build();
+        getLocalRoleReply reply;
+
+        reply = blockingStub.getLocalRole(request);
+        assertEquals(Optional.of(MastershipRole.MASTER),
+                MastershipRoleProtoTranslator.translate(reply.getMastershipRole()));
+    }
+
+    /**
+     * Tests the invocation result of requestRoleForSync method.
+     *
+     * @throws InterruptedException
+     */
+    @Test
+    public void testRequestRoleForSync() throws InterruptedException {
+        requestRoleForSyncRequest request = requestRoleForSyncRequest.newBuilder()
+                .setDeviceId(DEVICE_ID_2)
+                .build();
+        requestRoleForSyncReply reply;
+
+        reply = blockingStub.requestRoleForSync(request);
+        assertEquals(Optional.of(MastershipRole.STANDBY),
+                MastershipRoleProtoTranslator.translate(reply.getMastershipRole()));
+    }
+
+    /**
+     * Tests the invocation result of getMasterFor method.
+     *
+     * @throws InterruptedException
+     */
+    @Test
+    public void testGetMasterFor() {
+        getMasterForRequest request = getMasterForRequest.newBuilder()
+                .setDeviceId(DEVICE_ID_1)
+                .build();
+        getMasterForReply reply;
+
+        reply = blockingStub.getMasterFor(request);
+        assertEquals(nid1, NodeIdProtoTranslator.translate(reply.getNodeId()));
+    }
+
+    /**
+     * Tests the invocation result of getNodesFor method.
+     *
+     * @throws InterruptedException
+     */
+    @Test
+    public void testGetNodesFor() {
+        getNodesForRequest request = getNodesForRequest.newBuilder()
+                .setDeviceId(DEVICE_ID_3)
+                .build();
+        getNodesForReply reply;
+
+        reply = blockingStub.getNodesFor(request);
+        assertEquals(nid3, NodeIdProtoTranslator.translate(reply.getRoleInfo().getMaster()));
+    }
+
+    private class MockMastershipService implements MastershipService {
+
+        @Override
+        public MastershipRole getLocalRole(DeviceId deviceId) {
+            return mastershipMap.get(deviceId);
+        }
+
+        @Override
+        public CompletableFuture<MastershipRole> requestRoleFor(DeviceId deviceId) {
+            return null;
+        }
+
+        @Override
+        public MastershipRole requestRoleForSync(DeviceId deviceId) {
+            return mastershipMap.get(deviceId);
+        }
+
+        @Override
+        public CompletableFuture<Void> relinquishMastership(DeviceId deviceId) {
+            return null;
+        }
+
+        @Override
+        public void relinquishMastershipSync(DeviceId deviceId) {
+        }
+
+        @Override
+        public NodeId getMasterFor(DeviceId deviceId) {
+            return nodeIdMap.get(deviceId);
+        }
+
+        @Override
+        public RoleInfo getNodesFor(DeviceId deviceId) {
+            return roleInfoMap.get(deviceId);
+        }
+
+        @Override
+        public Set<DeviceId> getDevicesOf(NodeId nodeId) {
+            return null;
+        }
+
+        @Override
+        public void addListener(MastershipListener listener) {
+
+        }
+
+        @Override
+        public void removeListener(MastershipListener listener) {
+
+        }
+    }
+}