Many organizations are investigating the possibility of adopting open source software or migrating their mission critical applications to open platforms. In this context, defining an assurance process for large open source code bases has becomes of paramount importance, and can help in filling the gap with proprietary solutions.In this paper, we discuss how assurance has become a primary requirement for organizations wishing to adopt open source products. Then, we describe how bug tracking and fixing can be enriched to support a more general cycle of assurance, and we evaluate how this process can be applied to large-scale open source projects like JADE and WADE.