NB: It's modetest not testmode
You're right. It is available, but the output cannot be used (as root) under an X-server:
trying to open device 'radeon'...failed
trying to open device 'nouveau'...failed
trying to open device 'vmwgfx'...failed
.
.
trying to open device 'mxsfb-drm'...failed
no device found
Running modetest in a tty gives proper output, see https://paste.kodi.tv/uzidafiyeb
The videocard is a Geforce 7300LE (same family as the Geforce 6100).