tests: refactor common test infrastructure and fixtures

Change-Id: I597c11130eefa2cc2846ee6655c85dc04f2f22ef
diff --git a/tests/unit/util/notification-stream.t.cpp b/tests/unit/util/notification-stream.t.cpp
index ada10c5..2df3014 100644
--- a/tests/unit/util/notification-stream.t.cpp
+++ b/tests/unit/util/notification-stream.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018 Regents of the University of California,
+ * Copyright (c) 2014-2020 Regents of the University of California,
  *                         Arizona Board of Regents,
  *                         Colorado State University,
  *                         University Pierre & Marie Curie, Sorbonne University,
@@ -29,7 +29,7 @@
 #include "ndn-cxx/util/dummy-client-face.hpp"
 
 #include "tests/boost-test.hpp"
-#include "tests/unit/identity-management-time-fixture.hpp"
+#include "tests/unit/io-key-chain-fixture.hpp"
 #include "tests/unit/util/simple-notification.hpp"
 
 namespace ndn {
@@ -37,13 +37,14 @@
 namespace tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
-BOOST_FIXTURE_TEST_SUITE(TestNotificationStream, ndn::tests::IdentityManagementTimeFixture)
+BOOST_FIXTURE_TEST_SUITE(TestNotificationStream, ndn::tests::IoKeyChainFixture)
 
 BOOST_AUTO_TEST_CASE(Post)
 {
-  DummyClientFace face(io, m_keyChain);
-  util::NotificationStream<SimpleNotification> notificationStream(face,
-    "/localhost/nfd/NotificationStreamTest", m_keyChain);
+  DummyClientFace face(m_io, m_keyChain);
+  NotificationStream<SimpleNotification> notificationStream(face,
+                                                            "/localhost/nfd/NotificationStreamTest",
+                                                            m_keyChain);
 
   SimpleNotification event1("msg1");
   notificationStream.postNotification(event1);