diff --git a/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/FujitsuVoltAlertConfig.java b/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/FujitsuVoltAlertConfig.java
index fbefb5a..79d0b06 100644
--- a/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/FujitsuVoltAlertConfig.java
+++ b/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/FujitsuVoltAlertConfig.java
@@ -43,8 +43,8 @@
     private static final String VOLT_ALERTS = "volt-alerts";
     private static final String ALERT_FILTER = "alert-filter";
     private static final String NOTIFY_ALERT = "notify-alert";
-    private final Set<String> severityLevels = ImmutableSet.of(
-            "none", "info", "minor", "major", "critical");
+    private static final Set<String> SEVERITYLEVELS =
+            ImmutableSet.of("none", "info", "minor", "major", "critical");
     private static final String DISABLE = "disable";
 
 
@@ -61,29 +61,31 @@
             log.warn("Not master for {} Use {} to execute command",
                      ncDeviceId,
                      mastershipService.getMasterFor(ncDeviceId));
-            return reply;
+            return null;
         }
 
         try {
             StringBuilder request = new StringBuilder();
-            request.append(VOLT_NE_OPEN).append(VOLT_NE_NAMESPACE);
-            request.append(ANGLE_RIGHT).append(NEW_LINE);
-            request.append(buildStartTag(VOLT_ALERTS));
-            request.append(buildEmptyTag(ALERT_FILTER));
-            request.append(buildEndTag(VOLT_ALERTS));
-            request.append(VOLT_NE_CLOSE);
+            request.append(VOLT_NE_OPEN + VOLT_NE_NAMESPACE);
+            request.append(ANGLE_RIGHT + NEW_LINE);
+            request.append(buildStartTag(VOLT_ALERTS))
+                .append(buildEmptyTag(ALERT_FILTER))
+                .append(buildEndTag(VOLT_ALERTS))
+                .append(VOLT_NE_CLOSE);
 
-            reply = controller.
-                    getDevicesMap().get(ncDeviceId).getSession().
-                    get(request.toString(), REPORT_ALL);
+            reply = controller
+                    .getDevicesMap()
+                    .get(ncDeviceId)
+                    .getSession()
+                    .get(request.toString(), REPORT_ALL);
         } catch (IOException e) {
-            log.error("Cannot communicate to device {} exception ", ncDeviceId, e);
+            log.error("Cannot communicate to device {} exception {}", ncDeviceId, e);
         }
         return reply;
     }
 
     @Override
-    public void setAlertFilter(String severity) {
+    public boolean setAlertFilter(String severity) {
         DriverHandler handler = handler();
         NetconfController controller = handler.get(NetconfController.class);
         MastershipService mastershipService = handler.get(MastershipService.class);
@@ -94,34 +96,36 @@
             log.warn("Not master for {} Use {} to execute command",
                      ncDeviceId,
                      mastershipService.getMasterFor(ncDeviceId));
-            return;
+            return false;
         }
 
-        if (!severityLevels.contains(severity)) {
-            log.error("Invalid severity level: " + severity);
-            return;
+        if (!SEVERITYLEVELS.contains(severity)) {
+            log.error("Invalid severity level: {}", severity);
+            return false;
         }
 
         try {
             StringBuilder request = new StringBuilder();
-            request.append(VOLT_NE_OPEN).append(VOLT_NE_NAMESPACE);
-            request.append(ANGLE_RIGHT).append(NEW_LINE);
-            request.append(buildStartTag(VOLT_ALERTS));
-            request.append(buildStartTag(ALERT_FILTER, false));
-            request.append(severity);
-            request.append(buildEndTag(ALERT_FILTER));
-            request.append(buildEndTag(VOLT_ALERTS));
-            request.append(VOLT_NE_CLOSE);
+            request.append(VOLT_NE_OPEN + VOLT_NE_NAMESPACE);
+            request.append(ANGLE_RIGHT + NEW_LINE);
+            request.append(buildStartTag(VOLT_ALERTS))
+                .append(buildStartTag(ALERT_FILTER, false))
+                .append(severity)
+                .append(buildEndTag(ALERT_FILTER))
+                .append(buildEndTag(VOLT_ALERTS))
+                .append(VOLT_NE_CLOSE);
 
             controller.getDevicesMap().get(ncDeviceId).getSession().
                     editConfig(RUNNING, null, request.toString());
         } catch (IOException e) {
-            log.error("Cannot communicate to device {} exception ", ncDeviceId, e);
+            log.error("Cannot communicate to device {} exception {}", ncDeviceId, e);
+            return false;
         }
+        return true;
     }
 
     @Override
-    public void subscribe(String mode) {
+    public boolean subscribe(String mode) {
         DriverHandler handler = handler();
         NetconfController controller = handler.get(NetconfController.class);
         MastershipService mastershipService = handler.get(MastershipService.class);
@@ -132,13 +136,13 @@
             log.warn("Not master for {} Use {} to execute command",
                      ncDeviceId,
                      mastershipService.getMasterFor(ncDeviceId));
-            return;
+            return false;
         }
 
         if (mode != null) {
             if (!DISABLE.equals(mode)) {
-                log.error("Invalid mode: " + mode);
-                return;
+                log.error("Invalid mode: {}", mode);
+                return false;
             }
         }
 
@@ -148,15 +152,17 @@
                         endSubscription();
             } else {
                 StringBuilder request = new StringBuilder();
-                request.append(ANGLE_LEFT).append(NOTIFY_ALERT).append(SPACE);
-                request.append(VOLT_NE_NAMESPACE).append(SLASH).append(ANGLE_RIGHT);
+                request.append(ANGLE_LEFT + NOTIFY_ALERT + SPACE);
+                request.append(VOLT_NE_NAMESPACE + SLASH + ANGLE_RIGHT);
 
                 controller.getDevicesMap().get(ncDeviceId).getSession().
                         startSubscription(request.toString());
             }
         } catch (IOException e) {
-            log.error("Cannot communicate to device {} exception ", ncDeviceId, e);
+            log.error("Cannot communicate to device {} exception {}", ncDeviceId, e);
+            return false;
         }
+        return true;
     }
 
 }
diff --git a/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/behaviour/VoltAlertConfig.java b/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/behaviour/VoltAlertConfig.java
index 9385361..1007aee 100644
--- a/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/behaviour/VoltAlertConfig.java
+++ b/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/behaviour/VoltAlertConfig.java
@@ -36,13 +36,15 @@
      * Set alert filter severity level.
      *
      * @param severity input data in string
+     * @return true if success
      */
-    void setAlertFilter(String severity);
+    boolean setAlertFilter(String severity);
 
     /**
      * Subscribe to receive notifications or unsubscribe.
      *
      * @param mode disable subscription
+     * @return true if success
      */
-    void subscribe(String mode);
+    boolean subscribe(String mode);
 }
diff --git a/drivers/fujitsu/src/test/java/org/onosproject/drivers/fujitsu/FujitsuVoltAlertConfigTest.java b/drivers/fujitsu/src/test/java/org/onosproject/drivers/fujitsu/FujitsuVoltAlertConfigTest.java
new file mode 100644
index 0000000..2cef69c
--- /dev/null
+++ b/drivers/fujitsu/src/test/java/org/onosproject/drivers/fujitsu/FujitsuVoltAlertConfigTest.java
@@ -0,0 +1,306 @@
+/*
+ * 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.drivers.fujitsu;
+
+import org.apache.commons.io.IOUtils;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+
+import java.io.InputStream;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.fail;
+import static org.onosproject.drivers.fujitsu.FujitsuVoltXmlUtilityMock.*;
+
+
+/**
+ * Unit tests for methods of FujitsuVoltAlertConfig.
+ */
+public class FujitsuVoltAlertConfigTest {
+
+    private final FujitsuNetconfSessionListenerTest listener = new InternalSessionListener();
+
+    private static final String TEST_VOLT_ALERTS = "volt-alerts";
+    private static final String TEST_ALERT_FILTER = "alert-filter";
+    private static final String TEST_NOTIFY_ALERT = "notify-alert";
+
+    private static final String TEST_NOTIFY_ALERT_WITH_NAMESPACE =
+            TEST_ANGLE_LEFT + TEST_NOTIFY_ALERT + TEST_SPACE +
+            TEST_VOLT_NE_NAMESPACE;
+
+    private static final String NOTIFY_ALERT_FILE = "/notifyalert.xml";
+
+    private static final String[] INVALID_SET_TCS = {
+        ":abc",
+        "@critical",
+        "1234",
+    };
+    private static final String[] VALID_SET_TCS = {
+        "minor",
+        "critical",
+        "none",
+        "info",
+        "major",
+    };
+    private static final String[] VERIFY_NOTIFY_ALERT_FILE_TCS = {
+        "notify-alert",
+        "alert-seqnum",
+        "alert-type",
+        "alert-clear",
+        "severity",
+        "resource-id",
+        "ponlink-id",
+        "alert-time",
+        "date",
+        "time",
+    };
+    private Integer currentKey;
+    private FujitsuNetconfControllerMock controller;
+    private FujitsuDriverHandlerAdapter driverHandler;
+    private FujitsuVoltAlertConfig voltConfig;
+
+    @Before
+    public void setUp() throws Exception {
+        controller = new FujitsuNetconfControllerMock();
+        driverHandler = controller.setUp(listener);
+        voltConfig = new FujitsuVoltAlertConfig();
+        voltConfig.setHandler(driverHandler);
+    }
+
+    /**
+     * Run to verify handling of subscription.
+     */
+    @Test
+    public void testSubscribe() throws Exception {
+        assertTrue("Incorrect response", voltConfig.subscribe(null));
+        assertFalse("Incorrect response", voltConfig.subscribe("false"));
+        assertTrue("Incorrect response", voltConfig.subscribe("disable"));
+    }
+
+    /**
+     * Run to verify handling of subscription.
+     */
+    @Test
+    public void testGetAlertFilter() throws Exception {
+        voltConfig.getAlertFilter();
+    }
+
+    /**
+     * Run to verify handling of invalid input for set operation.
+     */
+    @Test
+    public void testInvalidSetAlertFilterInput() throws Exception {
+        String target;
+        boolean result;
+
+        for (int i = ZERO; i < INVALID_SET_TCS.length; i++) {
+            target = INVALID_SET_TCS[i];
+            result = voltConfig.setAlertFilter(target);
+            assertFalse("Incorrect response for ", result);
+        }
+    }
+
+    /**
+     * Run to verify handling of valid input for set operation.
+     */
+    @Test
+    public void testValidSetAlertFilter() throws Exception {
+        String target;
+        boolean result;
+
+        for (int i = ZERO; i < VALID_SET_TCS.length; i++) {
+            target = VALID_SET_TCS[i];
+            currentKey = i;
+            result = voltConfig.setAlertFilter(target);
+            assertTrue("Incorrect response for ", result);
+        }
+    }
+
+    /**
+     * Run to verify sample notify-alert components.
+     */
+    @Test
+    public void testNotifyAlert() throws Exception {
+        boolean result;
+        result = verifyNotifyAlert();
+        assertTrue("Incorrect response for ", result);
+    }
+
+    /**
+     * Verifies XML request string by comparing with generated string.
+     *
+     * @param request XML string for set operation
+     * @return true if XML string matches with generated
+     */
+    private boolean verifyGetRequest(String request) {
+        StringBuilder rpc = new StringBuilder();
+        rpc.append(TEST_VOLT_NE_OPEN + TEST_VOLT_NE_NAMESPACE);
+        rpc.append(TEST_ANGLE_RIGHT + TEST_NEW_LINE);
+        rpc.append(startTag(TEST_VOLT_ALERTS))
+            .append(emptyTag(TEST_ALERT_FILTER))
+            .append(endTag(TEST_VOLT_ALERTS))
+            .append(TEST_VOLT_NE_CLOSE);
+
+        String testRequest = rpc.toString();
+        String regex = TEST_WHITESPACES_REGEX;
+        int index = rpc.indexOf(regex);
+        while (index >= ZERO) {
+            testRequest = rpc.replace(index, index + regex.length(), TEST_EMPTY_STRING).toString();
+            request = request.replaceAll(regex, TEST_EMPTY_STRING);
+        }
+        boolean result = request.equals(testRequest);
+        assertTrue("Does not match with generated string", result);
+        return result;
+    }
+
+    /**
+     * Verifies XML request string by comparing with generated string.
+     *
+     * @param request XML string for set operation
+     * @return true or false
+     */
+    private boolean verifyEditConfigRequest(String request) {
+        StringBuilder rpc = new StringBuilder();
+        String target = VALID_SET_TCS[currentKey];
+
+        rpc.append(TEST_VOLT_NE_OPEN + TEST_VOLT_NE_NAMESPACE);
+        rpc.append(TEST_ANGLE_RIGHT + TEST_NEW_LINE);
+        rpc.append(startTag(TEST_VOLT_ALERTS))
+            .append(startTag(TEST_ALERT_FILTER, false))
+            .append(target)
+            .append(endTag(TEST_ALERT_FILTER))
+            .append(endTag(TEST_VOLT_ALERTS))
+            .append(TEST_VOLT_NE_CLOSE);
+
+        String testRequest = rpc.toString();
+        String regex = TEST_WHITESPACES_REGEX;
+        int index = rpc.indexOf(regex);
+        while (index >= ZERO) {
+            testRequest = rpc.replace(index, index + regex.length(), TEST_EMPTY_STRING).toString();
+            request = request.replaceAll(regex, TEST_EMPTY_STRING);
+        }
+        boolean result = request.equals(testRequest);
+        assertTrue("Does not match with generated string", result);
+        return result;
+    }
+
+    /**
+     * Verifies notify-alert XML.
+     */
+    private boolean verifyNotifyAlert() {
+        String testRequest;
+        String target;
+
+        try {
+            InputStream fileStream = getClass().getResourceAsStream(
+                    NOTIFY_ALERT_FILE);
+            testRequest = IOUtils.toString(fileStream, StandardCharsets.UTF_8);
+            testRequest = testRequest.substring(testRequest.indexOf(
+                    NOTIFY_ALERT_FILE) + NOTIFY_ALERT_FILE.length());
+        } catch (IOException e) {
+            fail("IOException while reading: " + NOTIFY_ALERT_FILE);
+            return false;
+        }
+
+        for (int i = ZERO; i < VERIFY_NOTIFY_ALERT_FILE_TCS.length; i++) {
+            target = VERIFY_NOTIFY_ALERT_FILE_TCS[i];
+            int index = testRequest.indexOf(target);
+                if (index < ZERO) {
+                    return false;
+                }
+        }
+        return true;
+    }
+
+    /**
+     * Internal listener for device service events.
+     */
+    private class InternalSessionListener implements FujitsuNetconfSessionListenerTest {
+        @Override
+        public boolean verifyEditConfig(String request) {
+            return false;
+        }
+
+        @Override
+        public boolean verifyEditConfig(String target, String mode, String request) {
+            boolean result;
+
+            assertTrue("Incorrect target", target.equals(TEST_RUNNING));
+            assertNull("Incorrect mode", mode);
+
+            request = request.replaceAll(TEST_DUPLICATE_SPACES_REGEX, TEST_SPACE);
+            assertTrue("Does not contain:" + TEST_VOLT_NAMESPACE,
+                    request.contains(TEST_VOLT_NAMESPACE));
+
+            result = verifyEditConfigRequest(request);
+            assertTrue("XML verification failure", result);
+            return result;
+        }
+
+        @Override
+        public boolean verifyGet(String filterSchema, String withDefaultsMode) {
+            boolean result;
+
+            assertTrue("Incorrect withDefaultsMode", withDefaultsMode.equals(TEST_REPORT_ALL));
+            filterSchema = filterSchema.replaceAll(TEST_DUPLICATE_SPACES_REGEX, TEST_SPACE);
+            assertTrue("Does not contain:" + TEST_VOLT_NAMESPACE,
+                    filterSchema.contains(TEST_VOLT_NAMESPACE));
+
+            result = verifyGetRequest(filterSchema);
+            assertTrue("XML verification failure", result);
+            return result;
+        }
+
+        @Override
+        public String buildGetReply() {
+            return null;
+        }
+
+        @Override
+        public boolean verifyWrappedRpc(String request) {
+            return false;
+        }
+
+        @Override
+        public void verifyStartSubscription(String filterSchema) {
+
+            filterSchema = filterSchema.replaceAll(TEST_DUPLICATE_SPACES_REGEX, TEST_SPACE);
+            assertTrue("Does not contain:" + TEST_NOTIFY_ALERT_WITH_NAMESPACE,
+                    filterSchema.contains(TEST_NOTIFY_ALERT_WITH_NAMESPACE));
+
+            StringBuilder rpc = new StringBuilder();
+            rpc.append(TEST_ANGLE_LEFT + TEST_NOTIFY_ALERT + TEST_SPACE);
+            rpc.append(TEST_VOLT_NE_NAMESPACE + TEST_SLASH + TEST_ANGLE_RIGHT);
+
+            String testRequest = rpc.toString();
+            String regex = TEST_WHITESPACES_REGEX;
+            int index = rpc.indexOf(regex);
+            while (index >= ZERO) {
+                testRequest = rpc.replace(index, index + regex.length(), TEST_EMPTY_STRING).toString();
+                filterSchema = filterSchema.replaceAll(regex, TEST_EMPTY_STRING);
+            }
+            assertTrue("Does not match with generated string",
+                    filterSchema.equals(testRequest));
+        }
+    }
+
+}
diff --git a/drivers/fujitsu/src/test/resources/notifyalert.xml b/drivers/fujitsu/src/test/resources/notifyalert.xml
new file mode 100644
index 0000000..f34cf50
--- /dev/null
+++ b/drivers/fujitsu/src/test/resources/notifyalert.xml
@@ -0,0 +1,32 @@
+<!--
+  ~ 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.
+  -->
+
+<notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
+  <eventTime>2016-09-19T14:11:31Z</eventTime>
+  <notify-alert xmlns="http://fujitsu.com/ns/volt/1.1">
+    <alert-seqnum>1120503006</alert-seqnum>
+    <resource-id>
+      <ponlink-id>1</ponlink-id>
+    </resource-id>
+    <alert-type>los</alert-type>
+    <alert-clear>false</alert-clear>
+    <severity>critical</severity>
+    <alert-time>
+      <date>2016-09-19</date>
+      <time>10:11:31</time>
+    </alert-time>
+  </notify-alert>
+</notification>