How to cope with the evolution of classic software during the test generation based on CPN

Software evolution is the process to meet the market requirements. The software after evolution has many new features worth of research. In this paper, we analyze the evolution of Linux, Windows, and Minix in detail, and analyzes from OSPF-v2 to OSPFv3 by RFC. The kernel call and system call of Minix3 and OSPF protocol are modeled with Colored Petri Net (CPN) Tools. Fork, as an example of system call, its CPN model is given. Reachable graph can be generated automatically from model with CPN. Then there is an algorithm for test generation based on reachable graph.