diff --git a/tests/unit/util/exception.t.cpp b/tests/unit/util/exception.t.cpp
index 33884dc..49ac2ab 100644
--- a/tests/unit/util/exception.t.cpp
+++ b/tests/unit/util/exception.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2019 Regents of the University of California.
+ * Copyright (c) 2013-2022 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,7 +28,7 @@
 
 namespace ndn {
 namespace exception {
-namespace test {
+namespace tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestException)
@@ -106,6 +106,6 @@
 BOOST_AUTO_TEST_SUITE_END() // TestException
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace test
+} // namespace tests
 } // namespace exception
 } // namespace ndn
diff --git a/tests/unit/util/sha256.t.cpp b/tests/unit/util/sha256.t.cpp
index 3340204..ae4fea3 100644
--- a/tests/unit/util/sha256.t.cpp
+++ b/tests/unit/util/sha256.t.cpp
@@ -29,27 +29,27 @@
 
 namespace ndn {
 namespace util {
-namespace test {
+namespace tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestSha256)
 
 BOOST_AUTO_TEST_CASE(Basic)
 {
-  const uint8_t input[] = {0x01, 0x02, 0x03, 0x04};
+  const uint8_t buf[] = {0x01, 0x02, 0x03, 0x04};
+  auto input = make_span(buf);
   auto expected = fromHex("9f64a747e1b97f131fabb6b447296c9b6f0201e79fb3c5356e6c77e89b6a806a");
 
   Sha256 statefulSha256;
   BOOST_CHECK_EQUAL(statefulSha256.empty(), true);
 
-  statefulSha256.update(input, 1);
-  statefulSha256.update(input + 1, 1);
-  statefulSha256.update(input + 2, 1);
-  statefulSha256.update(input + 3, 1);
+  statefulSha256.update(input.subspan(0, 1));
+  statefulSha256.update(input.subspan(1, 1));
+  statefulSha256.update(input.subspan(2, 1));
+  statefulSha256.update(input.subspan(3, 1));
   ConstBufferPtr digest = statefulSha256.computeDigest();
   BOOST_CHECK_EQUAL(digest->size(), Sha256::DIGEST_SIZE);
-  BOOST_CHECK_EQUAL_COLLECTIONS(expected->data(), expected->data() + expected->size(),
-                                digest->data(), digest->data() + digest->size());
+  BOOST_TEST(*digest == *expected, boost::test_tools::per_element());
 }
 
 BOOST_AUTO_TEST_CASE(ConstructFromStream)
@@ -63,8 +63,7 @@
   BOOST_CHECK_EQUAL(sha.toString(), "315F5BDB76D078C43B8AC0064E4A0164612B1FCE77C869345BFC94C75894EDD3");
 
   ConstBufferPtr digest = sha.computeDigest();
-  BOOST_CHECK_EQUAL_COLLECTIONS(expected->data(), expected->data() + expected->size(),
-                                digest->data(), digest->data() + digest->size());
+  BOOST_TEST(*digest == *expected, boost::test_tools::per_element());
 }
 
 BOOST_AUTO_TEST_CASE(Compare)
@@ -72,14 +71,13 @@
   const uint8_t origin[] = {0x01, 0x02, 0x03, 0x04};
 
   Sha256 digest1;
-  digest1.update(origin, sizeof(origin));
+  digest1.update(origin);
   digest1.computeDigest();
 
   Sha256 digest2;
-  digest2.update(origin, 1);
-  digest2.update(origin + 1, 1);
-  digest2.update(origin + 2, 1);
-  digest2.update(origin + 3, 1);
+  auto in = make_span(origin);
+  digest2.update(in.first(2));
+  digest2.update(in.last(2));
   digest2.computeDigest();
 
   BOOST_CHECK_EQUAL(digest1 == digest2, true);
@@ -98,8 +96,7 @@
   ConstBufferPtr digest = statefulSha256.computeDigest();
 
   BOOST_CHECK_EQUAL(statefulSha256.empty(), false);
-  BOOST_CHECK_EQUAL_COLLECTIONS(expected->data(), expected->data() + expected->size(),
-                                digest->data(), digest->data() + digest->size());
+  BOOST_TEST(*digest == *expected, boost::test_tools::per_element());
 }
 
 BOOST_AUTO_TEST_CASE(InsertionOperatorString)
@@ -112,8 +109,7 @@
   ConstBufferPtr digest = statefulSha256.computeDigest();
 
   BOOST_CHECK_EQUAL(statefulSha256.empty(), false);
-  BOOST_CHECK_EQUAL_COLLECTIONS(expected->data(), expected->data() + expected->size(),
-                                digest->data(), digest->data() + digest->size());
+  BOOST_TEST(*digest == *expected, boost::test_tools::per_element());
 }
 
 BOOST_AUTO_TEST_CASE(InsertionOperatorBlock)
@@ -138,8 +134,7 @@
   ConstBufferPtr digest = statefulSha256.computeDigest();
 
   BOOST_CHECK_EQUAL(statefulSha256.empty(), false);
-  BOOST_CHECK_EQUAL_COLLECTIONS(expected->data(), expected->data() + expected->size(),
-                                digest->data(), digest->data() + digest->size());
+  BOOST_TEST(*digest == *expected, boost::test_tools::per_element());
 }
 
 BOOST_AUTO_TEST_CASE(InsertionOperatorUint64t)
@@ -154,8 +149,7 @@
   ConstBufferPtr digest = statefulSha256.computeDigest();
 
   BOOST_CHECK_EQUAL(statefulSha256.empty(), false);
-  BOOST_CHECK_EQUAL_COLLECTIONS(expected->data(), expected->data() + expected->size(),
-                                digest->data(), digest->data() + digest->size());
+  BOOST_TEST(*digest == *expected, boost::test_tools::per_element());
 }
 
 BOOST_AUTO_TEST_CASE(Reset)
@@ -182,12 +176,10 @@
 
 BOOST_AUTO_TEST_CASE(StaticComputeDigest)
 {
-  const uint8_t input[] = {0x01, 0x02, 0x03, 0x04};
   auto expected = fromHex("9f64a747e1b97f131fabb6b447296c9b6f0201e79fb3c5356e6c77e89b6a806a");
 
-  ConstBufferPtr digest = Sha256::computeDigest(input, sizeof(input));
-  BOOST_CHECK_EQUAL_COLLECTIONS(expected->data(), expected->data() + expected->size(),
-                                digest->data(), digest->data() + digest->size());
+  ConstBufferPtr digest = Sha256::computeDigest({0x01, 0x02, 0x03, 0x04});
+  BOOST_TEST(*digest == *expected, boost::test_tools::per_element());
 }
 
 BOOST_AUTO_TEST_CASE(Print)
@@ -209,6 +201,6 @@
 BOOST_AUTO_TEST_SUITE_END() // TestSha256
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace test
+} // namespace tests
 } // namespace util
 } // namespace ndn
diff --git a/tests/unit/util/string-helper.t.cpp b/tests/unit/util/string-helper.t.cpp
index 8747301..a129c1a 100644
--- a/tests/unit/util/string-helper.t.cpp
+++ b/tests/unit/util/string-helper.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2019 Regents of the University of California.
+ * Copyright (c) 2013-2022 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -35,7 +35,7 @@
 
 namespace ndn {
 namespace util {
-namespace test {
+namespace tests {
 
 using boost::test_tools::output_test_stream;
 
@@ -85,12 +85,12 @@
 
 BOOST_AUTO_TEST_CASE(ToHex)
 {
-  std::string test = "Hello, world!";
-  BOOST_CHECK_EQUAL(toHex(reinterpret_cast<const uint8_t*>(test.data()), test.size()),
+  const std::string test = "Hello, world!";
+  BOOST_CHECK_EQUAL(toHex({reinterpret_cast<const uint8_t*>(test.data()), test.size()}),
                     "48656C6C6F2C20776F726C6421");
-  BOOST_CHECK_EQUAL(toHex(reinterpret_cast<const uint8_t*>(test.data()), test.size(), false),
+  BOOST_CHECK_EQUAL(toHex({reinterpret_cast<const uint8_t*>(test.data()), test.size()}, false),
                     "48656c6c6f2c20776f726c6421");
-  BOOST_CHECK_EQUAL(toHex(nullptr, 0), "");
+  BOOST_CHECK_EQUAL(toHex({}), "");
 
   Buffer buffer(test.data(), test.size());
   BOOST_CHECK_EQUAL(toHex(buffer, false),  "48656c6c6f2c20776f726c6421");
@@ -99,13 +99,13 @@
 
 BOOST_AUTO_TEST_CASE(FromHex)
 {
-  BOOST_CHECK(*fromHex("") == Buffer{});
-  BOOST_CHECK(*fromHex("48656c6c6f2c20776f726c6421") ==
-              (std::vector<uint8_t>{0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x2c, 0x20,
-                                    0x77, 0x6f, 0x72, 0x6c, 0x64, 0x21}));
-  BOOST_CHECK(*fromHex("012a3Bc4defAB5CdEF") ==
-              (std::vector<uint8_t>{0x01, 0x2a, 0x3b, 0xc4, 0xde,
-                                    0xfa, 0xb5, 0xcd, 0xef}));
+  BOOST_TEST(fromHex("")->empty());
+  const uint8_t expected1[] = {
+    0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x2c, 0x20, 0x77, 0x6f, 0x72, 0x6c, 0x64, 0x21
+  };
+  BOOST_TEST(*fromHex("48656c6c6f2c20776f726c6421") == expected1, boost::test_tools::per_element());
+  const uint8_t expected2[] = {0x01, 0x2a, 0x3b, 0xc4, 0xde, 0xfa, 0xb5, 0xcd, 0xef};
+  BOOST_TEST(*fromHex("012a3Bc4defAB5CdEF") == expected2, boost::test_tools::per_element());
 
   BOOST_CHECK_THROW(fromHex("1"), StringHelperError);
   BOOST_CHECK_THROW(fromHex("zz"), StringHelperError);
@@ -209,6 +209,6 @@
 BOOST_AUTO_TEST_SUITE_END() // TestStringHelper
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace test
+} // namespace tests
 } // namespace util
 } // namespace ndn