Software testing is the process of determining the precision, quality, completeness and security of the software systems. An important step in testing software is the generation of test cases, whose quality plays a vital role in determining the time for testing and subsequently its cost. In this research, it is shown that both structural and behavioural diagrams can be used to represent specifications in a single model using High Level Petri Nets (HLPN). This research focuses on automated generation of test models from Petri nets. Moreover, generating consistent formal models (HLPN) from informal models (UML) is the highlight of this research.