diff --git a/tests/block-literal.hpp b/tests/block-literal.hpp
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+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2018 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.
+ */
+
+#ifndef NAC_TESTS_BLOCK_LITERAL_HPP
+#define NAC_TESTS_BLOCK_LITERAL_HPP
+
+#include <ndn-cxx/encoding/block.hpp>
+#include <ndn-cxx/encoding/buffer-stream.hpp>
+#include <ndn-cxx/security/transform.hpp>
+
+namespace ndn {
+namespace nac {
+namespace tests {
+
+/** \brief Construct a \c Block from hexadecimal \p input.
+ *  \param input a string containing hexadecimal bytes and comments.
+ *               0-9 and upper-case A-F are input; all other characters are comments.
+ *  \param len length of \p input.
+ *  \throw security::transform::Error input has odd number of hexadecimal digits.
+ *  \throw tlv::Error input cannot be parsed into valid \c Block.
+ *
+ *  Example
+ *  \code
+ *  Block nameBlock = "0706 080141 080142"_block;
+ *  Block nackBlock = "FD032005 reason(no-route)=FD03210196"_block;
+ *  \endcode
+ */
+inline Block
+operator "" _block(const char* input, std::size_t len)
+{
+  namespace t = ndn::security::transform;
+  t::StepSource ss;
+  OBufferStream os;
+  ss >> t::hexDecode() >> t::streamSink(os);
+
+  for (const char* end = input + len; input != end; ++input) {
+    if (std::strchr("0123456789ABCDEF", *input) != nullptr) {
+      ss.write(reinterpret_cast<const uint8_t*>(input), 1);
+    }
+  }
+  ss.end();
+
+  return Block(os.buf());
+}
+
+} // namespace tests
+} // namespace nac
+} // namespace ndn
+
+#endif // NAC_TESTS_BLOCK_LITERAL_HPP