Power converter testing is a crucial, but time-consuming part of a switch-mode power supply (SMPS) design process, relying on expensive and often custom measurement setups. This makes it difficult to speed up and automate the test process. Thus, a flexible Python-based framework for automated characterization of ac/dc and dc/dc converters is proposed. In this framework, test configurations are defined using JSON scenario files that assign abstract roles like source, load, or measurement to the arbitrary instruments, irrespective of the vendor or interface. The abstraction enables a unified programming interface, supporting both legacy and modern measurement devices, simplifying the implementation of an automated test process. The testing flexibility is improved by using open-source adapters and standard communication protocols. For steady-state characterization, 2-D sweeps of input voltage and load current are performed. Experimental results are visualized as contour plots of efficiency, ripple, or temperature, offering deeper insights than traditional curves. This method allows for fast, simulation-like automated measurements with readily available instruments.