diff --git a/tests/unit-test-common-fixtures.hpp b/tests/unit-test-common-fixtures.hpp
new file mode 100644
index 0000000..03ba0f5
--- /dev/null
+++ b/tests/unit-test-common-fixtures.hpp
@@ -0,0 +1,92 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2018, Regents of the University of California
+ *
+ * NAC 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.
+ *
+ * NAC 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 NAC library authors and contributors.
+ */
+
+#ifndef NAC_TESTS_UNIT_TEST_COMMON_FIXTURES_HPP
+#define NAC_TESTS_UNIT_TEST_COMMON_FIXTURES_HPP
+
+#include "boost-test.hpp"
+#include "identity-management-fixture.hpp"
+
+#include <boost/asio.hpp>
+#include <ndn-cxx/util/time-unit-test-clock.hpp>
+
+namespace ndn {
+namespace nac {
+namespace tests {
+
+/** \brief base test fixture
+ *
+ *  Every test case should be based on this fixture,
+ *  to have per test case io_service initialization.
+ */
+class BaseFixture : public IdentityManagementFixture
+{
+protected:
+  BaseFixture();
+
+protected:
+  /** \brief reference to global io_service
+   */
+  boost::asio::io_service m_io;
+};
+
+/** \brief a base test fixture that overrides steady clock and system clock
+ */
+class UnitTestTimeFixture : public BaseFixture
+{
+protected:
+  UnitTestTimeFixture();
+
+  ~UnitTestTimeFixture();
+
+  /** \brief advance steady and system clocks
+   *
+   *  Clocks are advanced in increments of \p tick for \p nTicks ticks.
+   *  After each tick, global io_service is polled to process pending I/O events.
+   *
+   *  Exceptions thrown during I/O events are propagated to the caller.
+   *  Clock advancing would stop in case of an exception.
+   */
+  void
+  advanceClocks(const time::nanoseconds& tick, size_t nTicks = 1);
+
+  /** \brief advance steady and system clocks
+   *
+   *  Clocks are advanced in increments of \p tick for \p total time.
+   *  The last increment might be shorter than \p tick.
+   *  After each tick, global io_service is polled to process pending I/O events.
+   *
+   *  Exceptions thrown during I/O events are propagated to the caller.
+   *  Clock advancing would stop in case of an exception.
+   */
+  void
+  advanceClocks(const time::nanoseconds& tick, const time::nanoseconds& total);
+
+protected:
+  shared_ptr<time::UnitTestSteadyClock> steadyClock;
+  shared_ptr<time::UnitTestSystemClock> systemClock;
+
+  friend class LimitedIo;
+};
+
+} // namespace tests
+} // namespace nac
+} // namespace ndn
+
+#endif // NAC_TESTS_UNIT_TEST_COMMON_FIXTURES_HPP