A function for adaptively generating test vectors to verify the behavior of a digital system. The function utilizes one or more user-defined verification directives for directing the generation of the test vectors to areas of interest within the digital system. An emulator of the digital system provides dynamic feedback of internal state information to the test vector generation function during the verification. The test vector generation function adaptively generates future verification test vectors based on the user-defined verification directives in view of the internal state information feedback received from the emulator.