Week10b

Week10b - ©Ian Sommerville 2000 Slide 1 Verification and...

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Unformatted text preview: ©Ian Sommerville 2000 Slide 1 Verification and Validation ● Assuring that a software system meets a user's needs ● Objectives • To introduce software verification and validation and to discuss the distinction between them • To describe the program inspection process and its role in V & V • To explain static analysis as a verification technique ©Ian Sommerville 2000 Slide 2 ● Verification: "Are we building the product right" • The software should conform to its specification ● Validation: "Are we building the right product" • The software should do what the user really requires ● V & V must be applied at each stage in the software process ● Two principal objectives • Discovery of defects in a system • Assessment of whether the system is usable in an operational situation Verification vs. validation ©Ian Sommerville 2000 Slide 3 ● STATIC – Software inspections • Concerned with analysis of the static system representation to discover problems • May be supplement by tool-based document and code analysis ● DYNAMIC – Software testing • Concerned with exercising and observing product behaviour • The system is executed with test data and its operational behaviour is observed Static and dynamic verification ©Ian Sommerville 2000 Slide 4 ● Can reveal the presence of errors, not their absence ● A successful test is a test which discovers one or more errors ● The only validation technique for non-functional requirements ● Should be used in conjunction with static verification to provide full V&V coverage Program testing ©Ian Sommerville 2000 Slide 5 ● Defect testing • Tests designed to discover system defects. • A successful defect test is one which reveals the presence of defects in a system. ● Statistical testing • Tests designed to reflect the frequency of user inputs • Used for reliability estimation ● To be covered in the next lecture Types of testing ©Ian Sommerville 2000 Slide 6 V & V goals ● Verification and validation should establish confidence that the software is fit for purpose ● This does not mean completely free of defects ● Rather, it must be good enough for its intended use • The type of use will determine the degree of confidence that is needed ©Ian Sommerville 2000...
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Week10b - ©Ian Sommerville 2000 Slide 1 Verification and...

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