tests: sync common testing infrastructure with ndn-cxx and NFD

And upgrade waf to version 2.0.21

Change-Id: Id713e0f3035badd97ca7fc03f76e50085b9a266c
diff --git a/tests/io-fixture.hpp b/tests/io-fixture.hpp
new file mode 100644
index 0000000..881065c
--- /dev/null
+++ b/tests/io-fixture.hpp
@@ -0,0 +1,59 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2014-2020,  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 ndn-tools (Named Data Networking Essential Tools).
+ * See AUTHORS.md for complete list of ndn-tools authors and contributors.
+ *
+ * ndn-tools 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.
+ *
+ * ndn-tools 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
+ * ndn-tools, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef NDN_TOOLS_TESTS_IO_FIXTURE_HPP
+#define NDN_TOOLS_TESTS_IO_FIXTURE_HPP
+
+#include "tests/clock-fixture.hpp"
+
+#include <boost/asio/io_service.hpp>
+
+namespace ndn {
+namespace tests {
+
+class IoFixture : public ClockFixture
+{
+private:
+  void
+  afterTick() final
+  {
+    if (m_io.stopped()) {
+#if BOOST_VERSION >= 106600
+      m_io.restart();
+#else
+      m_io.reset();
+#endif
+    }
+    m_io.poll();
+  }
+
+protected:
+  boost::asio::io_service m_io;
+};
+
+} // namespace tests
+} // namespace ndn
+
+#endif // NDN_TOOLS_TESTS_IO_FIXTURE_HPP