Conclusion

Design by Contract is certainly not a core practice of XP, but neither does it contradict the XP values. It has been shown that Design by Contract does offer benefits in an XP environment, if wisely applied. In particular, large systems efforts can use contracts to specify and document their subsystems' semantics to a certain degree.

The authors are currently applying the approach described here in their projects. An empirical analysis of its success will show to what extent the described effects will benefit large XP projects.