diff --git a/site_utils/pubsub_utils_unittest.py b/site_utils/pubsub_utils_unittest.py
new file mode 100644
index 0000000..8a7c60a
--- /dev/null
+++ b/site_utils/pubsub_utils_unittest.py
@@ -0,0 +1,156 @@
+#!/usr/bin/env python
+#
+# Copyright 2016 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+import unittest
+
+import mox
+
+from apiclient import discovery
+from oauth2client.client import ApplicationDefaultCredentialsError
+from oauth2client.client import GoogleCredentials
+from googleapiclient.errors import UnknownApiNameOrVersion
+
+import common
+import pubsub_utils
+
+
+class MockedPubSub(object):
+    """A mocked PubSub handle."""
+    def __init__(self, test, topic, msg, retry, ret_val=None,
+            raise_except=False):
+        self.test = test
+        self.topic = topic
+        self.msg = msg
+        self.retry = retry
+        self.ret_val = ret_val
+        self.raise_except = raise_except
+
+    def projects(self):
+        """Mocked PubSub projects."""
+        return self
+
+    def topics(self):
+        """Mocked PubSub topics."""
+        return self
+
+    def publish(self, topic, body):
+        """Mocked PubSub publish method.
+
+        @param topic: PubSub topic string.
+        @param body: PubSub notification body.
+        """
+        self.test.assertEquals(self.topic, topic)
+        self.test.assertEquals(self.msg, body['messages'][0])
+        return self
+
+    def execute(self, num_retries):
+        """Mocked PubSub execute method.
+
+        @param num_retries: Number of retries.
+        """
+        self.test.assertEquals(self.num_retries, num_retries)
+        if self.raise_except:
+            raise Exception()
+        return self.ret
+
+
+def _create_sample_message():
+    """Creates a sample pubsub message."""
+    msg_payload = {'data': 'sample data'}
+    msg_attributes = {}
+    msg_attributes['var'] = 'value'
+    msg_payload['attributes'] = msg_attributes
+
+    return msg_payload
+
+
+class PubSubTests(mox.MoxTestBase):
+    """Tests for pubsub related functios."""
+
+    def test_get_pubsub_service_no_service_account(self):
+        """Test getting the pubsub service"""
+        self.mox.StubOutWithMock(os.path, 'isfile')
+        os.path.isfile(pubsub_utils.CLOUD_SERVICE_ACCOUNT_FILE).AndReturn(False)
+        self.mox.ReplayAll()
+        pubsub = pubsub_utils._get_pubsub_service()
+        self.assertIsNone(pubsub)
+        self.mox.VerifyAll()
+
+    def test_get_pubsub_service_with_invalid_service_account(self):
+        """Test getting the pubsub service"""
+        self.mox.StubOutWithMock(os.path, 'isfile')
+        self.mox.StubOutWithMock(GoogleCredentials, 'from_stream')
+        os.path.isfile(pubsub_utils.CLOUD_SERVICE_ACCOUNT_FILE).AndReturn(True)
+        credentials = self.mox.CreateMock(GoogleCredentials)
+        GoogleCredentials.from_stream(
+                pubsub_utils.CLOUD_SERVICE_ACCOUNT_FILE).AndRaise(
+                        ApplicationDefaultCredentialsError())
+        self.mox.ReplayAll()
+        pubsub = pubsub_utils._get_pubsub_service()
+        self.assertIsNone(pubsub)
+        self.mox.VerifyAll()
+
+    def test_get_pubsub_service_with_invalid_service_account(self):
+        """Test getting the pubsub service"""
+        self.mox.StubOutWithMock(os.path, 'isfile')
+        self.mox.StubOutWithMock(GoogleCredentials, 'from_stream')
+        os.path.isfile(pubsub_utils.CLOUD_SERVICE_ACCOUNT_FILE).AndReturn(True)
+        credentials = self.mox.CreateMock(GoogleCredentials)
+        GoogleCredentials.from_stream(
+                pubsub_utils.CLOUD_SERVICE_ACCOUNT_FILE).AndReturn(credentials)
+        credentials.create_scoped_required().AndReturn(True)
+        credentials.create_scoped(pubsub_utils.PUBSUB_SCOPES).AndReturn(
+                credentials)
+        self.mox.StubOutWithMock(discovery, 'build')
+        discovery.build(pubsub_utils.PUBSUB_SERVICE_NAME,
+                pubsub_utils.PUBSUB_VERSION,
+                credentials=credentials).AndRaise(UnknownApiNameOrVersion())
+        self.mox.ReplayAll()
+        pubsub = pubsub_utils._get_pubsub_service()
+        self.assertIsNone(pubsub)
+        self.mox.VerifyAll()
+
+    def test_get_pubsub_service_with_service_account(self):
+        """Test getting the pubsub service"""
+        self.mox.StubOutWithMock(os.path, 'isfile')
+        self.mox.StubOutWithMock(GoogleCredentials, 'from_stream')
+        os.path.isfile(pubsub_utils.CLOUD_SERVICE_ACCOUNT_FILE).AndReturn(True)
+        credentials = self.mox.CreateMock(GoogleCredentials)
+        GoogleCredentials.from_stream(
+                pubsub_utils.CLOUD_SERVICE_ACCOUNT_FILE).AndReturn(credentials)
+        credentials.create_scoped_required().AndReturn(True)
+        credentials.create_scoped(pubsub_utils.PUBSUB_SCOPES).AndReturn(
+                credentials)
+        self.mox.StubOutWithMock(discovery, 'build')
+        discovery.build(pubsub_utils.PUBSUB_SERVICE_NAME,
+                pubsub_utils.PUBSUB_VERSION,
+                credentials=credentials).AndReturn(1)
+        self.mox.ReplayAll()
+        pubsub = pubsub_utils._get_pubsub_service()
+        self.assertIsNotNone(pubsub)
+        self.mox.VerifyAll()
+
+    def test_publish_notifications(self):
+        """Tests publish notifications."""
+        self.mox.StubOutWithMock(pubsub_utils, '_get_pubsub_service')
+        msg = _create_sample_message()
+        pubsub_utils._get_pubsub_service().AndReturn(MockedPubSub(
+            self,
+            'test_topic',
+            msg,
+            pubsub_utils._PUBSUB_NUM_RETRIES,
+            # use tuple ('123') instead of list just for easy to write the test.
+            ret_val = {'messageIds', ('123')}))
+
+        self.mox.ReplayAll()
+        pubsub_utils.publish_notifications(
+                'test_topic', [msg])
+        self.mox.VerifyAll()
+
+
+if __name__ == '__main__':
+    unittest.main()