Comment by softwhale

I'm pretty sure that Rockstar North would have some tests in place. The creators of the reverse engineered project, simply couldn't access these tests as they wouldn't be included in the build. (At least, I'd imagine). Also: It may be interesting to note that GTA:V's leaked build logs featured some notes about an "auto play bot test failed at {mission}". I'm pretty sure they would have to have similar tests (although perhaps at a smaller scale) for older GTA's as well.