add encoding unit tests

Change-Id: I319a34a760742e6125e6a28c4ddc23fcf2f29cb3
diff --git a/src/detail/probe-encoder.hpp b/src/detail/probe-encoder.hpp
index 0a991c3..0db8cb9 100644
--- a/src/detail/probe-encoder.hpp
+++ b/src/detail/probe-encoder.hpp
@@ -31,7 +31,7 @@
 public:
   // For Client use
   static Block
-  encodeApplicationParameters(std::vector<std::tuple<std::string, std::string>>&& parameters);
+  encodeApplicationParameters(const std::vector<std::tuple<std::string, std::string>>& parameters);
 
   static void
   decodeDataContent(const Block& block, std::vector<std::pair<Name, int>>& availableNames,