Disclosed herein are computer-implemented method, system, and computer-program product (non-transitory computer-readable storage medium) embodiments for automatic test-pattern generation (ATPG) validation. An embodiment includes parsing an ATPG input, semantically analyzing the ATPG input, generating a first HDL model based on the semantic analysis, creating an HDL testbench based on the first HDL model, simulating an ATE test of a circuit structure, and outputting a validation result of the circuit structure, based on the simulating. In some embodiments, the parsing may include lexical and/or syntactic analysis. The HDL model may represent the circuit structure as functionally equivalent to the ATPG input, as determined based on the semantic analysis. In some embodiments, the ATPG input includes a cycle-based test pattern for a first block of the ATPG input, and the HDL testbench includes event-based test patterns that mimic given ATE behavior. The HDL model may be smaller in size than the ATPG input.