I have been looking for a native speed testing app for BlackBerry 10 and have yet to find a good one. So far Android ports have proven to be unreliable. The team over at BBItalia noticed a new app called Speed Tester from Blackswan that promises to provide speed testing in a mobile app. I have nothing to compare the results against but it does seem to work nicely over WiFi and cellular data. The interface is a bit clunky and not cascades but it does work. Best of all its free!
Check out Speed Tester free in BlackBerry World