Page - 45 - in The Future of Software Quality Assurance

The Tester SkillsProgram 45 The most common diagram one sees is the figure eight or infinite loop below. The principle is that the plan, code, build, test throughrelease, deploy,operate and monitorphasesare sequentialbutare repeatedforevery release. But there’s a problem here. If you unwrap the infinite loop, you can see that the phases are very much like the stages of a Waterfall development. There are no feedbackloops,youhave toassumeonephasecompletesbeforeanotherstarts. So, it appears that Continuous Delivery is just Waterfall in the small. What do weknowaboutwaterfall-styledevelopments? • It’s sequential––onestage followsanother––novariation • Dependenciesrule––youcan’t startonestagebefore thepreviousstage isdone • It’snot re-entrant––noflexibility to react to externalevents • Testing has stages itself––we know that testing has itself stages of thinking and activities spread throughthe process • Only one phase of testing––but there are developer and tester manuals and automated test executionactivities • Testing is squeezed––timeboxedactivities––the thinking,preparationandexecu- tion time isall limited • No feedback loop(s)––we know that testing finds bugs––but the continuous processhasnofeedback loop. If Agile has taught us anything, it’s that the dependence on staged approaches madeWaterfall unsuccessful in moredynamicenvironments.