Spec Explorer 2010 for Visual Studio is a visual tool for modeling software behavior and generating test suites from those models. Spec Explorer’s approach to model-based testing has been shown to greatly enhance productivity of test case creation, to ensure predictability of requirement coverage, and to support lifecycle management and software updates. Models are typically written in C# and controlled by a configuration language which allows to express scenarios and test purposes. Microsoft itself chose Spec Explorer as a cornerstone of the effort to validate open protocol documentation, developing more than 200 test suites validating over 40,000 requirements for networking protocols in a production environment.
SpecExplorer: Model-Based Testing made practicable:
Wolfgang Grieskamp and Keith Stobie: Spec Explorer - An Overview: