Verification and Validation Perspectives

1. Verification and Validation Perspectives

2. Validation Activities Ensure that the right functions are performed Verification Activities Ensure that the these functions are performed right and are reliable

3. Validation, failures and QA Activities • System testing, where the focus is the overall set of system functions to be provided to users; • Acceptance testing and beta testing, where the focus is the assessment of software acceptance or performance by users; • Usage-based statistical testing, where the operational environment by target users is simulated during software testing before product release; • Software fault tolerance, which focuses on providing continued service expected by customers even when local problems exist; • Software safety assurance activities, which focus on providing the expected accident-freeoperations or reducing accident damage when an accident is unavoidable.

4. Verification, Conformance and QA Activities • Check the conformance of a software system to its specifications. • The assumption is there is a well-defined set of specifications • All activities dealing directly with faults, errors or error sources

5. Verification and Validation in Software Processes • Many specific QA activities deal with both the verification and the validation aspects. For example, different types of testing can be classified either as verification test or validation test or contain both elements: The focus of the acceptance test is clearly validation, while that for unit test is verification, however, system test contains both the verification and validation components. • The situation with inspection as an important defect reduction activity is similar to testing above. However, due to the absence of execution and direct observations of failures, inspection is more closely connected to verification than to validation. For example, most of the inspection activities are performed on software code or design, which are classical verification activities. The less used requirement inspections and usage scenarios based inspections are closer to validation. • Defect prevention deals with error source elimination and error blocking, while both verification and validation deal with failures and faults. Therefore, there is no direct connection between defect prevention and the V&V view of QA activities, but only indirectly through the target of preventive actions. For example, if the target is eliminating ambiguity in the requirement or the product domain knowledge, it is indirectly connected to validation. If the target is to block syntactic faults or other faults due to the proper selection and usage of processes, methodologies, technologies, or tools, it is indirectly connected to verification.

6. Verification and Validation in Software Processes • Closely related to both defect prevention and formalized inspection is the use of formal method as a QA activity. The formal specification part is close to validation, but indirectly, much like the defect prevention activities above. The formal verification part naturally falls into verification activities, verifying the program or design correctness with respect to its formal specifications. • Defect containment activities, such as through fault tolerance and safety assurance, are more closely related to validation activities than verification due to their focus on avoiding global failures or minimizing failure damages under actual operational environments. However, when such defect containment features are specific for a software system or an embedded system, the conformance to this part of the specification can be treated much the same as other verification activities to check the general conformance to specifications.

7. QA Activities: Mapping from defect-centered view to V & V view