util: Porting NotificationSubscriber, FaceMonitor, and NotificationStream from NFD

New generic classes:
- `util::NotificationSubscriber` (`util/notification-subscriber.hpp`)
- `util::NotificationStream` (`util/notification-stream.hpp`)

NFD Face monitoring class:
- `nfd::FaceMonitor` (`management/nfd-face-monitor.hpp`)

Change-Id: I2ab0a2cd9d7e3ac07036f290f0b4de5eb16e6e38
diff --git a/tests/unit-tests/util/notification-stream.cpp b/tests/unit-tests/util/notification-stream.cpp
new file mode 100644
index 0000000..0378bd1
--- /dev/null
+++ b/tests/unit-tests/util/notification-stream.cpp
@@ -0,0 +1,90 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+/**
+ * Original copyright notice from NFD:
+ *
+ * Copyright (c) 2014,  Regents of the University of California,
+ *                      Arizona Board of Regents,
+ *                      Colorado State University,
+ *                      University Pierre & Marie Curie, Sorbonne University,
+ *                      Washington University in St. Louis,
+ *                      Beijing Institute of Technology,
+ *                      The University of Memphis
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "util/notification-stream.hpp"
+#include "simple-notification.hpp"
+
+#include "boost-test.hpp"
+#include "../dummy-client-face.hpp"
+
+namespace ndn {
+namespace tests {
+
+BOOST_AUTO_TEST_SUITE(UtilNotificationStream)
+
+BOOST_AUTO_TEST_CASE(Post)
+{
+  shared_ptr<DummyClientFace> face = makeDummyClientFace();
+  ndn::KeyChain keyChain;
+  util::NotificationStream<SimpleNotification> notificationStream(*face,
+    "/localhost/nfd/NotificationStreamTest", keyChain);
+
+  SimpleNotification event1("msg1");
+  notificationStream.postNotification(event1);
+  face->processEvents();
+  BOOST_REQUIRE_EQUAL(face->m_sentDatas.size(), 1);
+  BOOST_CHECK_EQUAL(face->m_sentDatas[0].getName(),
+                    "/localhost/nfd/NotificationStreamTest/%FE%00");
+  SimpleNotification decoded1;
+  BOOST_CHECK_NO_THROW(decoded1.wireDecode(face->m_sentDatas[0].getContent().blockFromValue()));
+  BOOST_CHECK_EQUAL(decoded1.getMessage(), "msg1");
+
+  SimpleNotification event2("msg2");
+  notificationStream.postNotification(event2);
+  face->processEvents();
+  BOOST_REQUIRE_EQUAL(face->m_sentDatas.size(), 2);
+  BOOST_CHECK_EQUAL(face->m_sentDatas[1].getName(),
+                    "/localhost/nfd/NotificationStreamTest/%FE%01");
+  SimpleNotification decoded2;
+  BOOST_CHECK_NO_THROW(decoded2.wireDecode(face->m_sentDatas[1].getContent().blockFromValue()));
+  BOOST_CHECK_EQUAL(decoded2.getMessage(), "msg2");
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace tests
+} // namespace ndn