A method is presented and described for testing of at least one electronic control system, in which the control system is connected via a data channel to a test device, at least one environmental model is calculated on the test device and the environmental model interacts with the control system by output of environment model data via the test device to the control system and by receiving control system data from the control system via the data channel. The method according to the invention executes on the test device at least one test model to influence the environment model and/or to calculate the environment model and/or the electronic control system, in which the test model or the test models is or are executed functionally independently of the environment model and, during test operation, synchronously with the environment model.