ROS (Robot Operating System) is an open source community in robotics that is developing standard robotics operating system facilities such as hardware abstraction, low-level device control, communication middleware, and a wide range of software components for robotics functionality. This paper studies the quality assurance practices of the ROS community. We use qualitative methods to understand how ideology, priorities of the community, culture, sustainability, complexity, and adaptability of the community affect the implementation of quality assurance practices. Our analysis suggests that software engineering practices require social and cultural alignment and adaptation to the community particularities to achieve seamless implementation in open source environments. This alignment should be incorporated into the design and implementation of quality assurance practices in open source communities.