1. A computer program product for use in conjunction with a computer system, the computer program product configured to direct the computer system to verify operation of a specified system, the computer program product comprising a computer readable storage medium and a computer program mechanism embedded therein, the computer program mechanism comprising: verification procedures for interconnection with a set of simulation procedures so as to interleave performance of system verification operations with system simulation operations; the verification procedures including instructions for executing a test bench so as to define operational correctness and/or performance criteria for the specified system, the operational correctness and/or performance criteria including an Expect Event, the Expect Event comprising a combination of one or more signal values that are expected to occur during simulation of the specified system, and a time frame during which the signal value combination is expected to occur; wherein the time frame for the Expect Event has a specified simulation start time and a specified nonzero, finite duration; and the verification procedures including instructions for blocking execution of a thread of execution associated with the test bench until the earlier of the combination of one or more signal values occurring during simulation of the specified system and the time frame expiring.