refactor code

Change-Id: Ia2bc49ed8742d79000fd59f7e95fa9b957573c54
diff --git a/tests/tree-generator.hpp b/tests/tree-generator.hpp
new file mode 100644
index 0000000..3544ac7
--- /dev/null
+++ b/tests/tree-generator.hpp
@@ -0,0 +1,56 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014,  Regents of the University of California
+ *
+ * This file is part of NSL (NDN Signature Logger).
+ * See AUTHORS.md for complete list of NSL authors and contributors.
+ *
+ * NSL is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NSL 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NSL, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of nsl authors and contributors.
+ */
+
+#ifndef NSL_TESTS_TREE_GENERATOR_HPP
+#define NSL_TESTS_TREE_GENERATOR_HPP
+
+#include "sub-tree-binary.hpp"
+
+namespace nsl {
+namespace tests {
+
+class TreeGenerator
+{
+public:
+  static ndn::ConstBufferPtr
+  getHash(const Node::Index& idx,
+          const NonNegativeInteger& nextLeafSeqNo,
+          bool useEmpty = true);
+
+  static shared_ptr<SubTreeBinary>
+  getSubTreeBinary(const Node::Index& index,
+                   const NonNegativeInteger& nextLeafSeqNo,
+                   bool useEmpty = true);
+
+  static ndn::ConstBufferPtr
+  getLeafHash();
+
+public:
+  static const Name LOGGER_NAME;
+
+private:
+  static ndn::ConstBufferPtr LEAF_HASH;
+};
+
+} // namespace tests
+} // namespace nsl
+
+#endif // NSL_TESTS_TREE_GENERATOR_HPP