  This paper discusses a model-based approach to validate software requirements
in agile development processes by simulation and in particular automated
testing. The use of models as central development artifact needs to be added to
the portfolio of software engineering techniques, to further increase
efficiency and flexibility of the development beginning already early in the
requirements definition phase. Testing requirements are some of the most
important techniques to give feedback and to increase the quality of the
result. Therefore testing of artifacts should be introduced as early as
possible, even in the requirements definition phase.
