rename folders

Change-Id: Id70266deeefd066b03b146a13b5279eb8474d7f4
diff --git a/tests/unit-tests/challenge-credential.t.cpp b/tests/unit-tests/challenge-credential.t.cpp
index cc5a8ac..46eccb2 100644
--- a/tests/unit-tests/challenge-credential.t.cpp
+++ b/tests/unit-tests/challenge-credential.t.cpp
@@ -18,7 +18,7 @@
  * See AUTHORS.md for complete list of ndncert authors and contributors.
  */
 
-#include "challenge-module/challenge-credential.hpp"
+#include "challenge-modules/challenge-credential.hpp"
 #include "test-common.hpp"
 #include <ndn-cxx/security/signing-helpers.hpp>
 #include <ndn-cxx/util/io.hpp>