Chapter 22

Discuss the differences between verification and validation, and explain why validation is a particularly difficult process.

Explain why it is not necessary for a program to be completely free of defects before it is delivered to its customers. To what extent can testing be used to validate that the program is fit for its purpose?

Explain why program inspections are an effective technique for discovering errors in a program. What types of error are unlikely to be discovered through inspections?

Suggest why an organisation with a competitive, elitist culture would probably find it difficult to introduce program inspections as a V \& V technique.

Using your knowledge of Java, $\mathrm{C}++,\mathrm{C}$ or some other programming language, derive a checklist of common errors (not syntax errors) that could not be detected by a compiler but that might be detected in a program inspection.

Explain why it may be cost-effective to use formal methods in the development of safetycritical software systems. Why do you think that some developers of this type of system are against the use of formal methods?

A manager decides to use the reports of program inspections as an input to the staff appraisal process. These reports show who made and who discovered program errors. Is this ethical managerial behaviour? Would it be ethical if the staff were informed in advance that this would happen? What difference might it make to the inspection process?

One approach that is commonly adopted to system testing is to test the system until the testing budget is exhausted and then deliver the system to customers. Discuss the ethics of this approach.