Software Quality Assurance in XP and Spiral - A Comparative Study

Agile processes have been introduced to avoid the problems most of software practitioners have run up against by using traditional software development methodologies. These are well known for their benefits like focus on quality, early business value delivery, higher morale of stakeholders, and the reduced cost/schedule. Also, they can support the earlier and quicker production of the code by dividing the product into small segments called iterations. However, there are on-going debates about their flexibility to accommodate changing requirements and whether the productivity and quality of the agile processes is satisfactory for the customers or not. Previously available studies have mostly focused on comparing XP(eXtreme Programming) with some other agile methodologies, rather than comparing it with traditional plan-driven software development methodologies. In this paper, we identify the XP phases and practices, how they ensure product quality, and map XP phases against the Spiral model phases to prove that XP has built-in QA (quality assurance) practices in its life cycle, in addition to its focus on productivity. A case study is also included to empirically investigate quality of the product developed using XP with comparison to the product developed using Spiral model.