util: NetworkMonitor helper to detect network state changes

This commit includes only OS X implementation using CoreFoundation framework

Change-Id: I8d5488ec5780e2a33bb20595391208a76b9e69dd
Refs: #2443
diff --git a/tests/integrated/network-monitor.cpp b/tests/integrated/network-monitor.cpp
new file mode 100644
index 0000000..9ed4bb3
--- /dev/null
+++ b/tests/integrated/network-monitor.cpp
@@ -0,0 +1,56 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2015 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.
+ */
+
+#define BOOST_TEST_MAIN 1
+#define BOOST_TEST_DYN_LINK 1
+#define BOOST_TEST_MODULE ndn-cxx Integrated Tests (Network Monitor)
+
+#include "util/network-monitor.hpp"
+
+#include "boost-test.hpp"
+#include <cstdlib>
+#include <iostream>
+#include "util/time.hpp"
+
+namespace ndn {
+namespace util {
+
+BOOST_AUTO_TEST_SUITE(UtilNetworkMonitor)
+
+BOOST_AUTO_TEST_CASE(Basic)
+{
+  boost::asio::io_service io;
+  BOOST_REQUIRE_NO_THROW((NetworkMonitor(io)));
+
+  NetworkMonitor monitor(io);
+
+  monitor.onNetworkStateChanged.connect([] {
+      std::cout << time::toString(time::system_clock::now())
+                << "\tReceived network state change event" << std::endl;
+    });
+
+  io.run();
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace util
+} // namespace ndn