Refactor and modernize namespace declarations

 * Completely remove inline namespace v2
 * Flatten some unnecessarily deep namespace nesting
 * Move DummyClientFace, Segmenter, SegmentFetcher to namespace ndn
 * Move all unit tests to namespace ndn::tests

Change-Id: I8bcfcf9fd669936a3277d2d5d505f765b4b05742
diff --git a/tests/unit/security/validator-config.t.cpp b/tests/unit/security/validator-config.t.cpp
index 391879d..7cdfa53 100644
--- a/tests/unit/security/validator-config.t.cpp
+++ b/tests/unit/security/validator-config.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -29,11 +29,7 @@
 #include "tests/key-chain-fixture.hpp"
 #include "tests/unit/security/validator-config/common.hpp"
 
-namespace ndn {
-namespace security {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_FIXTURE_TEST_SUITE(TestValidatorConfig, KeyChainFixture)
@@ -42,12 +38,12 @@
 
 BOOST_AUTO_TEST_CASE(Construct)
 {
-  util::DummyClientFace face;
+  DummyClientFace face;
 
   ValidatorConfig v1(face);
   BOOST_CHECK_EQUAL(v1.m_policyConfig.m_isConfigured, false);
 
-  ValidatorConfig v2(make_unique<CertificateFetcherOffline>());
+  ValidatorConfig v2(make_unique<security::CertificateFetcherOffline>());
   BOOST_CHECK_EQUAL(v2.m_policyConfig.m_isConfigured, false);
 }
 
@@ -56,7 +52,7 @@
 public:
   ValidatorConfigFixture()
     : path(boost::filesystem::path(UNIT_TESTS_TMPDIR) / "security" / "validator-config")
-    , validator(make_unique<CertificateFetcherOffline>())
+    , validator(make_unique<security::CertificateFetcherOffline>())
   {
     boost::filesystem::create_directories(path);
     config = R"CONF(
@@ -118,11 +114,11 @@
 
 BOOST_AUTO_TEST_CASE(FromSection)
 {
-  validator.load(validator_config::tests::makeSection(config), "config-file-from-section");
+  validator.load(makeSection(config), "config-file-from-section");
   BOOST_CHECK_EQUAL(validator.m_policyConfig.m_isConfigured, true);
 
   // should reload policy
-  validator.load(validator_config::tests::makeSection(config), "config-file-from-section");
+  validator.load(makeSection(config), "config-file-from-section");
   BOOST_CHECK_EQUAL(validator.m_policyConfig.m_isConfigured, true);
 }
 
@@ -133,7 +129,7 @@
 {
   validator.load(configFile);
 
-  InterestSigner signer(m_keyChain);
+  security::InterestSigner signer(m_keyChain);
   auto i = signer.makeCommandInterest("/hello/world/CMD", signingWithSha256());
   size_t nValidated = 0, nFailed = 0;
 
@@ -155,7 +151,7 @@
 {
   validator.load(configFile);
 
-  InterestSigner signer(m_keyChain);
+  security::InterestSigner signer(m_keyChain);
   Interest i1("/hello/world");
   signer.makeSignedInterest(i1);
   size_t nValidated = 0, nFailed = 0;
@@ -179,7 +175,7 @@
 {
   validator.load(configFile);
 
-  InterestSigner signer(m_keyChain);
+  security::InterestSigner signer(m_keyChain);
   auto i1 = signer.makeCommandInterest("/hello/world");
   size_t nValidated = 0, nFailed = 0;
 
@@ -200,6 +196,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidatorConfig
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests