Why would that matter in the case of testing for correctness? I thought these 'runable spec' implementations were only to verify that the output of the 'real' i

Why would that matter in the case of testing for correctness? I thought these 'runable spec' implementations were only to verify that the output of the 'real' implementation is correct and thus would never even be used anywhere that could/would be attacked. Am I not understanding the purpose correctly?