diff --git a/tests/daemon/limited-io.hpp b/tests/daemon/limited-io.hpp
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+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2014-2019,  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/>.
+ */
+
+#ifndef NFD_TESTS_DAEMON_LIMITED_IO_HPP
+#define NFD_TESTS_DAEMON_LIMITED_IO_HPP
+
+#include "tests/test-common.hpp"
+
+#include <exception>
+
+namespace nfd {
+namespace tests {
+
+/** \brief provides IO operations limit and/or time limit for unit testing
+ *
+ *  \warning LimitedIo is incompatible with RibIoFixture
+ */
+class LimitedIo : noncopyable
+{
+public:
+  explicit
+  LimitedIo(UnitTestTimeFixture* uttf = nullptr);
+
+  /// indicates why run() returns
+  enum StopReason {
+    /// g_io.run() returns normally because there's no work to do
+    NO_WORK,
+    /// .afterOp() has been invoked nOpsLimit times
+    EXCEED_OPS,
+    /// nTimeLimit has elapsed
+    EXCEED_TIME,
+    /// an exception is thrown
+    EXCEPTION
+  };
+
+  /** \brief g_io.run() with operation count and/or time limit
+   *  \param nOpsLimit operation count limit, pass UNLIMITED_OPS for no limit
+   *  \param timeLimit time limit, pass UNLIMITED_TIME for no limit
+   *  \param tick if this LimitedIo is constructed with UnitTestTimeFixture,
+   *              this is passed to .advanceClocks(), otherwise ignored
+   */
+  StopReason
+  run(int nOpsLimit, const time::nanoseconds& timeLimit,
+      const time::nanoseconds& tick = time::milliseconds(1));
+
+  /// count an operation
+  void
+  afterOp();
+
+  /** \brief defer for specified duration
+   *
+   *  equivalent to .run(UNLIMITED_OPS, d)
+   */
+  void
+  defer(const time::nanoseconds& d)
+  {
+    this->run(UNLIMITED_OPS, d);
+  }
+
+  std::exception_ptr
+  getLastException() const
+  {
+    return m_lastException;
+  }
+
+private:
+  /** \brief an exception to stop IO operation
+   */
+  class StopException : public std::exception
+  {
+  };
+
+  void
+  afterTimeout();
+
+public:
+  static const int UNLIMITED_OPS;
+  static const time::nanoseconds UNLIMITED_TIME;
+
+private:
+  UnitTestTimeFixture* m_uttf;
+  StopReason m_reason;
+  int m_nOpsRemaining = 0;
+  scheduler::EventId m_timeout;
+  std::exception_ptr m_lastException;
+  bool m_isRunning = false;
+};
+
+} // namespace tests
+} // namespace nfd
+
+#endif // NFD_TESTS_DAEMON_LIMITED_IO_HPP