A system and method automatically ensures consistency among a design model and one or more test models that test the design model. The system may include a broker adapted to construct an interface specification. The interface specification identifies the interface of the design model, e.g., its external inputs, external outputs, and initialization states. It may also identify the outputs, inputs, and initialization setting objects of the test models. Proposed changes to the design model's interface may be captured by the broker, and applied to the design model and to the test models atomically. Proposed changes to a given test model that implicate the design model's interface also may be captured, and applied to the given test model, the other test models, and the design model atomically. Default behaviors may be defined for applying the proposed changes to the other test models and the design model.