Effective implementation of test automation requires taking testing into account in the system design. In short, this is called design for testability (DFT). In this paper a study on DFT in component-based embedded software is presented, based on the interviews and technical documentation from two large-scale companies in the European telecom industry. The way test automation is addressed and the different techniques applied to make this more effective at the architectural level are described. The differences and benefits of different approaches are discussed.