1. A radio device testing system comprising: a radio device having a software radio stack including a plurality of logical layers through which radio messages comprising data are processed in accordance with a radio protocol; test control means for controlling and monitoring testing of said radio device via a link therebetween; and stack perturbation means, linked to said software radio stack and to said test control means, for, under control of said test control means, altering data of a radio message en route through one of said plurality of logical layers of said software radio stack, by: receiving the radio message at a first layer of said plurality of logical layers of said software radio stack, the radio message comprising one or more fields; creating a modified radio message by modifying data of one of the fields of the received radio message; and transferring the modified radio message to a second layer of said plurality of logical layers of said software radio stack.