In the last two decades, software architecture has played a central role in the development of software systems. It provides a high-level description for large-size and complex systems using suitable bstractions of the system's components and their interactions. In our work, the software architecture is described using a formal Architecture Description Language (ADL) designed in the ArchWare European Project, pi -ADL-C&C. One of the purposes of this ADL is to allow formal validation of an implemented system with respect to its architectural model. In this paper, we propose a conformance testing approach for validating a software system with respect to its architecture. The architectural abstract test cases are derived from an Input-Output Symbolic Transition System (IOSTS) representing the architecture structure and behaviors, which are then translated into concrete test cases to be executed on the system under test. To illustrate our approach we use the coffee machine example.