As more teams embrace the challenges of continuous delivery, we hear lots of people talking about "shift left" and "shift right" in a testing context. What does that mean, exactly, and why does everyone want to do it?
When Software Development Was Linear
I joined my first "waterfall" process project back in the mid-1980s, as a developer. It was a linear progression, and in my head, I saw it unfurl from left to right. It seemed reasonable (to my naive eyes) to start with a thorough analysis of the system to be built, finding out what the customers wanted. This "phase" produced an analysis document which triggered the "requirements phase," during which analysts and product managers created a document detailing every bit of functionality to be built. And on it went, handoffs from one phase, and often one team, to the next, with thick Word documents changing hands, until the developers finally "froze" the code so that no more changes could be done. Finally, QA could start the testing phase, usually with very little time left until the release deadline!