Refactor and modernize namespace declarations

Move all unit tests to namespace nfd::tests

Delete unused header core/algorithm.hpp

Change-Id: I5591f0c5f3bb5db67f8b45fae95471f8a555ca68
diff --git a/tests/daemon/face/tcp-transport-fixture.hpp b/tests/daemon/face/tcp-transport-fixture.hpp
index 4b382a8..2ea4a2b 100644
--- a/tests/daemon/face/tcp-transport-fixture.hpp
+++ b/tests/daemon/face/tcp-transport-fixture.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2019,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -33,25 +33,15 @@
 #include "tests/daemon/limited-io.hpp"
 #include "tests/daemon/face/dummy-link-service.hpp"
 
-namespace nfd {
-namespace face {
-namespace tests {
+namespace nfd::tests {
 
-using namespace nfd::tests;
 namespace ip = boost::asio::ip;
 using ip::tcp;
+using face::TcpTransport;
 
 class TcpTransportFixture : public GlobalIoFixture
 {
 protected:
-  TcpTransportFixture()
-    : transport(nullptr)
-    , remoteSocket(g_io)
-    , receivedPackets(nullptr)
-    , acceptor(g_io)
-  {
-  }
-
   void
   startAccept(const tcp::endpoint& remoteEp)
   {
@@ -103,7 +93,7 @@
     transport = static_cast<TcpTransport*>(face->getTransport());
     receivedPackets = &static_cast<DummyLinkService*>(face->getLinkService())->receivedPackets;
 
-    BOOST_REQUIRE_EQUAL(transport->getState(), TransportState::UP);
+    BOOST_REQUIRE_EQUAL(transport->getState(), face::TransportState::UP);
   }
 
   void
@@ -120,18 +110,16 @@
 
 protected:
   LimitedIo limitedIo;
-  TcpTransport* transport;
+  TcpTransport* transport = nullptr;
   tcp::endpoint localEp;
-  tcp::socket remoteSocket;
-  std::vector<RxPacket>* receivedPackets;
+  tcp::socket remoteSocket{g_io};
+  std::vector<RxPacket>* receivedPackets = nullptr;
 
 private:
-  tcp::acceptor acceptor;
+  tcp::acceptor acceptor{g_io};
   unique_ptr<Face> face;
 };
 
-} // namespace tests
-} // namespace face
-} // namespace nfd
+} // namespace nfd::tests
 
 #endif // NFD_TESTS_DAEMON_FACE_TCP_TRANSPORT_FIXTURE_HPP