The main goal of this thesis is the realization of a an automatic test adapter for AC power testing of multi-voltage switching power supplies. The entire project has been carried out at SPEA Spa (TO) - an automatic test equipment company leader in the market - which helped me throughout the design of the fixture and the test program, giving me precious insights and a valuable testing technical knowledge. The whole document is divided into sections, starting from an introduction necessary to offer a theoretical background and proceeding with the blueprint of the adapter, covering its electrical design and the test program development.