In this paper we propose a new approach that addresses both the problems of design validation and hardware testing since the early stages of the design flow. The approach consists in adapting the mutation testing, a software method, to circuits described in VHDL. At the functional level, the approach behaves as a design validation method and at the hardware level as a classical ATPG. Standard software test metrics are used for assessing the quality of the design validation process, and the hardware fault coverage for assessing the test quality at the hardware level. An enhancement process that allows design validation to be efficiently reused for hardware testing is detailed. The approach is shown to be efficient upon a set of representative circuits.