Valid serialized data are stored in "cases.mpac" and "cases_compact.mpac". These files describe same objects. And "cases.json" describes an array of the described objects.
Thus you can verify your implementations as comparing the objects.
The crosslang tool reads serialized data from stdin and writes re-serialize data to stdout.
There are C++ and Ruby implementation of crosslang tool. You can verify your implementation as comparing that implementations.
$ cd ../cpp && ./configure && make && make install
or
$ port install msgpack # MacPorts
$ g++ -Wall crosslang.cc -lmsgpack -o crosslang
$ ./crosslang
Usage: ./crosslang [in-file] [out-file]
$ gem install msgpack
or
$ port install rb_msgpack # MacPorts
$ ruby crosslang.rb
Usage: crosslang.rb [in-file] [out-file]