tests: respect naming conventions and improve nesting of some test suites

Change-Id: I255c27b552b32570871a9d5f8bda814ba8723c80
Refs: #2497
diff --git a/tests/unit-tests/security/validity-period.t.cpp b/tests/unit-tests/security/validity-period.t.cpp
index be5b2e4..db22b9e 100644
--- a/tests/unit-tests/security/validity-period.t.cpp
+++ b/tests/unit-tests/security/validity-period.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2013-2015 Regents of the University of California.
+ * Copyright (c) 2013-2016 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,7 +28,8 @@
 namespace security {
 namespace test {
 
-BOOST_AUTO_TEST_SUITE(SecurityValidityPeriod)
+BOOST_AUTO_TEST_SUITE(Security)
+BOOST_AUTO_TEST_SUITE(TestValidityPeriod)
 
 BOOST_AUTO_TEST_CASE(ConstructorSetter)
 {
@@ -184,7 +185,8 @@
   BOOST_CHECK(validity1 != validity3);
 }
 
-BOOST_AUTO_TEST_SUITE_END()
+BOOST_AUTO_TEST_SUITE_END() // TestValidityPeriod
+BOOST_AUTO_TEST_SUITE_END() // Security
 
 } // namespace test
 } // namespace security