About ten years ago, auditors ran test packages against critical application to ensure that the test transactions produced the consistent results. If the test package produced any irregularities, they would be detected and the cause isolated and rectified. The test package was an excellent tool particularly for high volume, high value applications. It worked best in a batch or online data entry, batch update application. The technique fell out of favor because it was labor intensive and was considered by some to cause the auditor to lose independence.
Preemptive testing is essential for web-based applications.
If your company is a major online stockbroker, imagine the public relations disaster that would surely result if hackers grabbed that accounts and passwords for customer trading accounts. Armed with this data, the hackers could receive online statements or make unauthorized trades to the customer accounts, which could trigger capital gains taxes. There is no tolerance for error with online banking, investment, or order entry systems. Therefore I believe that it is time to preemptively audit these applications. Having said that, you are probably wondering what a preemptive audit consists of.