Open Source Software (OSS) is software products available to the public, with its source code to study, change, and improves its design. Open Source Software Development (OSSD) is the process by which open source software is developed within the confines of software engineering life-cycle methods. However when open source used for commercial purpose, then an open source license is required. Open source software is very often developed in a public and collaborative manner. The quality assurance principle under open source software development is an approach to improve software product quality against traditional methods and techniques. Despite the fact that the open source developments have seen remarkable successful in recent years, there are a number of product quality issues and challenges facing the open source development model. Many industries and business sectors are following or using OSSD, since they realize the benefits, but they do have some reservations concerning quality assurance in the form of program code quality, maintenance of the code and its quality, over the life-cycle of the product and third party usage. This paper reviews the literature of the process of the latest quality assurance, under open source software development methods and techniques. The result from this review is to show the process of quality assurance of open source software and that how it can affect the overall quality assurance principal.