Validation Obligations: A Novel Approach to Check Compliance between Requirements and their Formal Specification
This addresses a gap in formal methods for software quality assurance, specifically for validation in refinement-based development, though it appears incremental as it builds on existing verification frameworks.
The paper tackles the problem of catching mistakes in requirements or their interpretation too late in formal refinement-based development by introducing 'validation obligations' to check compliance between requirements and formal specifications earlier in the process.
Traditionally, practitioners use formal methods pre-dominately for one half of the quality-assurance process: verification (do we build the software right?). The other half -- validation (do we build the right software?) -- has been given comparatively little attention. While verification is the core of refinement-based formal methods, where each new refinement step must preserve all properties of its abstract model, validation is usually postponed until the latest stages of the development, when models can be automatically executed. Thus mistakes in requirements or in their interpretation are caught too late: usually at the end of the development process. In this paper, we present a novel approach to check compliance between requirements and their formal refinement-based specification during the earlier stages of development. Our proposed approach -- "validation obligations" -- is based on the simple idea that both verification and validation are an integral part of all refinement steps of a system.