Integrating Extreme Programming and Contracts

Extreme Programming (XP) is a light-weight software engineering methodology conceived by KENT BECK with a strong focus on business value. Design by Contract is a software design technique defined by BERTRAND MEYER that stresses stability and maintainability of large systems. The two are regarded as incompatible by many of their respective followers. In this paper, the authors describe why contracts can nonetheless offer benefits to XP, and how they can be used in an XP environment. Contracts are particularly helpful in large systems development, an area that is not yet well investigated by the XP community. The authors describe how applying Design by Contract in an XP project can work, and what benefits can be expected.