A system and method for generating test vectors includes generating traces of a system model or program stored in memory using a simulation engine. Simulated inputs are globally optimized using a fitness objective computed using a computer processing device. The simulation inputs are adjusted in accordance with feedback from the traces and fitness objective values by computing a distance between the fitness objective value and a reachability objective. Test input vectors are output based upon optimized fitness objective values associated with the simulated inputs to test the system model or program stored in memory.