Access retropie_setup by using sudo ./RetroPie-Setup/retropie_setup.sh
Select option 3 Setup / Configuration (to be used post install)
Select option SNESDev (Driver for the RetroPie GPIO-Adapter)
Reboot pi after installed
I think this will install jstest as well as the driver for the adapter. It should enable your controller ports though. It looks like you have it wired up correctly, just be sure none of those wires are shoring with others. Be sure you connect it in the correct direction on your adapter however as well as connecting the adapter to the pi in the correct direction.