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

Change-Id: Ia136e4bb074c14e8d824f563594cbc0ad7592c3b
Refs: #3655
diff --git a/tests/key-chain-fixture.hpp b/tests/key-chain-fixture.hpp
new file mode 100644
index 0000000..bf4e004
--- /dev/null
+++ b/tests/key-chain-fixture.hpp
@@ -0,0 +1,105 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2016 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDN_TESTS_KEY_CHAIN_FIXTURE_HPP
+#define NDN_TESTS_KEY_CHAIN_FIXTURE_HPP
+
+#include "security/key-chain.hpp"
+
+#include "boost-test.hpp"
+#include "identity-management-fixture.hpp"
+
+#include <boost/filesystem.hpp>
+
+namespace ndn {
+namespace tests {
+
+/**
+ * @brief Fixture to adjust/restore NDN_CLIENT_PIB and NDN_CLIENT_TPM paths
+ *
+ * Note that the specified PATH will be removed after fixture is destroyed.
+ * **Do not specify non-temporary paths.**
+ */
+template<class Path>
+class PibDirFixture
+{
+public:
+  PibDirFixture()
+    : m_pibDir(Path().PATH)
+  {
+    if (getenv("NDN_CLIENT_PIB") != nullptr) {
+      m_oldPib = getenv("NDN_CLIENT_PIB");
+    }
+    if (getenv("NDN_CLIENT_TPM") != nullptr) {
+      m_oldTpm = getenv("NDN_CLIENT_TPM");
+    }
+
+    /// @todo Consider change to an in-memory PIB/TPM
+    setenv("NDN_CLIENT_PIB", ("pib-sqlite3:" + m_pibDir).c_str(), true);
+    setenv("NDN_CLIENT_TPM", ("tpm-file:" + m_pibDir).c_str(), true);
+  }
+
+  ~PibDirFixture()
+  {
+    if (!m_oldPib.empty()) {
+      setenv("NDN_CLIENT_PIB", m_oldPib.c_str(), true);
+    }
+    else {
+      unsetenv("NDN_CLIENT_PIB");
+    }
+
+    if (!m_oldTpm.empty()) {
+      setenv("NDN_CLIENT_TPM", m_oldTpm.c_str(), true);
+    }
+    else {
+      unsetenv("NDN_CLIENT_TPM");
+    }
+
+    boost::filesystem::remove_all(m_pibDir);
+  }
+
+protected:
+  const std::string m_pibDir;
+
+private:
+  std::string m_oldPib;
+  std::string m_oldTpm;
+};
+
+struct DefaultPibDir
+{
+  const std::string PATH = "build/keys";
+};
+
+/**
+ * @brief Fixture to create a test KeyChain with default identity
+ */
+class KeyChainFixture : public PibDirFixture<DefaultPibDir>,
+                        public IdentityManagementFixture
+{
+public:
+  KeyChainFixture();
+};
+
+} // namespace tests
+} // namespace ndn
+
+#endif // NDN_TESTS_KEY_CHAIN_FIXTURE_HPP