A testbench for testing a device under test (DUT), wherein the testbench has a verification environment including a reference model, a scoreboard and a customized agent for each interface that the DUT needs to receive input from and/or transmit output on. The testbench system is able to be generated by a testbench builder that automatically creates a scoreboard, a reference model, a dispatcher and generic agents including generic drivers, loopback ports, sequencers and/or generic monitors for each interface and then automatically customize the generic agents based on their corresponding interface such that the agents meet the requirements of the interface for the DUT.