1. A method for configuring a test device set up for testing an electronic control unit via a configuration system, the method comprising: executing a software model of a technical system in the test device, the software model communicating via an input/output interface of the test device with a device connected to the test device, the configuration system having a first configuration element of a first element type and a second configuration element of a second element type, assigning properties of the test device to the configuration elements, a communication between the connected device and the software model being configured with the properties; sorting the properties in the configuration system, the sorting being switchable between sorting types, the sorting types including a union set sort, an intersection sort, and a condensing sort; and sorting the properties of the union set sort such that the properties assigned to the first configuration element form a joined set that contains only the properties assigned to the first configuration element, and the properties assigned to the second element form a joined set that contains only the properties assigned to the second configuration element, wherein the intersection sort sorts the properties such that a joined set of the properties is formed whose assigned configuration elements are of the same element type, and wherein the condensing sort occurs such that a joined set is formed of the properties that are included in both the first and second configuration elements.