Tracing at the Most Basic Level, Requirements

¶ … Tracing

At the most basic level, requirements tracing demonstrates that software does what it is intended to do (Davis, A.M., and Leffingwell). According to Davis and Lefffingwell, tracing verifies that all user needs are implemented and that there are no extra system behaviors that cannot be traced to a user requirement. While extra functionality may not seem like a problem, it means extra time, money and effort to develop and can be a source of defects (Foster, 2001). Requirements tracing also assists in prioritization, testing and system quality and change management.

With regards to prioritization, tracing ensures that developers first work on implementing the requirements which are the most important, thus increasing the chances of completing a product or project on schedule (Foster, 2001). This is because tracing identifies which code components implement the highest priority requirements. Testers are also able to verify the most important functionality to determine when and if the first versions of the systems are ready to release (Foster, 2001).

Testing and system quality as well as change management also benefit greatly from requirements tracing. If a low-level requirement fails during requirements testing, it is absolutely clear which high-level requirements will not be met (Capps, 2002). Also, if there is a defect, all of the areas that will be affected based on the requirements tracing "tree" can be identified. When high-level requirements change, a developer knows what lower-level objects need to change (Capps, 2002). What appears to be a simple request might actually involve changes to many parts of a system and requirements tracing helps the developer estimate the work involved (Foster, 2001). For projects that are subject to broad or continual change, this benefit alone may justify requirements tracing.