Rename 'tests/unit-tests' directory to 'tests/unit'

Change-Id: I78ea29938259fac288781bed12fb2399ac7eba26
diff --git a/tests/unit/util/placeholders.t.cpp b/tests/unit/util/placeholders.t.cpp
new file mode 100644
index 0000000..0dc8c70
--- /dev/null
+++ b/tests/unit/util/placeholders.t.cpp
@@ -0,0 +1,46 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2018 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.
+ */
+
+// Bug 2109 test case
+
+// interest.hpp includes common.hpp; common.hpp shouldn't be used from external program
+#include "interest.hpp"
+
+// util/config-file.hpp indirectly includes <boost/property_tree/ptree.hpp>
+// which in turn imports Boost placeholders
+#include "util/config-file.hpp"
+
+// It's intentional to write "using namespace",
+// to simulate an external program linked against ndn-cxx.
+using namespace ndn;
+
+void
+placeholdersTestFunction(int i)
+{
+}
+
+int
+placeholdersTestMain()
+{
+  auto f = std::bind(&placeholdersTestFunction, _1);
+  f(1);
+  return 0;
+}