tests: sync common testing infrastructure with ndn-cxx

Also upgrade waf to version 2.0.21

Change-Id: Ibfd3386772d48df287b6be73e6d778d3661abe86
diff --git a/tests/io-fixture.hpp b/tests/io-fixture.hpp
new file mode 100644
index 0000000..d15a8ed
--- /dev/null
+++ b/tests/io-fixture.hpp
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2013-2020  Regents of the University of California
+ *                          The University of Memphis
+ *
+ * This file is part of PSync.
+ *
+ * PSync 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.
+ *
+ * PSync 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 a copy of the GNU Lesser General Public License along with
+ * PSync, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef PSYNC_TESTS_IO_FIXTURE_HPP
+#define PSYNC_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 // PSYNC_TESTS_IO_FIXTURE_HPP