I guess you are aware of the test possibilities in transaction SM59? Client and Server test programs are included in the Classical RFC SDK. There are also examples in the NetWeaver RFC SDK which can be used to test RFC connections. See the attached links for details.
http://help.sap.com/saphelp_nw73ehp1/helpdata/en/48/a06855d4666b81e10000000a42189c/frameset.htm
http://help.sap.com/saphelp_nw73ehp1/helpdata/en/48/a06bb1d4666b81e10000000a42189c/frameset.htm