Forgot to add the files related to the work done for guidelines for package tests organisation (http://developer.symbian.org/wiki/index.php/Guidelines_for_Package_Test_Organisation).
To get the test working you need the 3 following files that are currently missing in S^3:
mpxtest1.mp3
mpxtest2.mp3
mpxtestplaylist.m3u
If you have access to S^2 code, then you can copy these 3 files from:
https://developer-secure.symbian.org/sfl/MCL/sf/app/musicplayer/file/1141fa6821ce/musicplayer_plat/mpx_music_player_app_api/tsrc/data/mmc
A bug has been raised to track that work: http://developer.symbian.org/bugs/show_bug.cgi?id=2384