tests: Enable isolation of KeyChain during run of unit/integrated tests

Change-Id: Ia136e4bb074c14e8d824f563594cbc0ad7592c3b
Refs: #3655
diff --git a/tests/unit-tests/security/sec-rule-relative.t.cpp b/tests/unit-tests/security/sec-rule-relative.t.cpp
index 8557cc9..a94e6c1 100644
--- a/tests/unit-tests/security/sec-rule-relative.t.cpp
+++ b/tests/unit-tests/security/sec-rule-relative.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).
  *
@@ -26,6 +26,8 @@
 namespace security {
 namespace tests {
 
+using namespace ndn::tests;
+
 BOOST_FIXTURE_TEST_SUITE(SecuritySecRuleRelative, IdentityManagementFixture)
 
 BOOST_AUTO_TEST_CASE(SecRuleRelativeTest)