Modern embedded systems are increasingly complex and contain multiple software layers from BSP (Board Support Packages) to OS to middleware to AI (Artificial Intelligence) algorithms like perception and voice recognition. Integrations of inter-layer and intra-layer in embedded systems provide dedicated services such as taking a picture or movie-streaming. Accordingly, it gets more complicated to find out the root cause of a system failure. This industrial proposal describes a difficulty of testing embedded systems, and presents a case study in terms of integration testing.