Citation :
Within the software group, there are subgroups and subcultures. But what could be divisive office politics in other organizations is actually a critical part of the process. The central group breaks down into two key teams: the coders - the people who sit and write code -- and the verifiers -- the people who try to find flaws in the code. The two outfits report to separate bosses and function under opposing marching orders. The development group is supposed to deliver completely error-free code, so perfect that the testers find no flaws at all. The testing group is supposed to pummel away at the code with flight scenarios and simulations that reveal as many flaws as possible. The result is what Tom Peterson calls "a friendly adversarial relationship." "They're in competition for who's going to find the errors," says Keller. "Sometimes they fight like cats and dogs. The developers want to catch all their own errors. The verifiers get mad, 'Hey, give it up! You're taking away from our time to test the software!'" The developers have even begun their own formal inspections of the code in carefully moderated sessions, a rigorous proof-reading they hope will confound the testers. The verifiers, in turn, argue that they deserve credit for some errors found before they even start testing. "From the verification group's perspective," says Pat McLellan, a senior manager, "we're aware that if there was no independent verification group, the developers would tend to be more lax. Just the presence of our group makes them more careful." The results of this friendly rivalry: the shuttle group now finds 85% of its errors before formal testing begins, and 99.9% before the program is delivered to NASA.
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