Abstract: A configuration system for configuring a test system suitable for testing an electronic control unit, wherein a configuration diagram has a plurality of hierarchy elements, and a hierarchy element either has one hierarchy element or multiple hierarchy elements or no hierarchy element. The hierarchy element has an identifier, and wherein a hierarchy element has port(s) or no port, and wherein at least one hierarchy element is assigned to a functional property of the test system to be configured, wherein in an expanded view mode, the hierarchy elements are displayed at least partially nested and the ports and identifiers are shown one below the other, wherein in an at least partially collapsed view mode, a first set of hierarchy elements is shown such that the identifiers are shown side by side, wherein the ports and identifiers remain visible and the hierarchical relationship of the hierarchy elements remains displayed.