Testing a Requirements Pattern Language through Reverse Engineering

This paper looks at a case study to reverse engineer an IT system that supports the Health and Safety Executive in making planning recommendations with respect to hazardous installations. It compares a Use Case model created from a requirements specification with a Use Case model derived from an inspection of the built system. The objective is to discover how accurately the final system could be predicted using a series of requirements patterns. Through the application of requirements patterns, it was possible to predict the functionality delivered to a high degree, which suggests this is a useful contribution to the prediction of functionality and thereby to system sizing. This work is part of a bigger project for the Health and Safety Executive investigating improvements to system sizing/effort estimation and its impact on the management of complexity.