How Do Verification and Validation Differ?

TL;DR

Verification asks whether the product is being built correctly during each development phase, while validation asks whether the completed product is the right one. Verification mainly uses reviews, inspections, walkthroughs, unit testing, and integration testing; validation dynamically tests the complete system against the SRS document and customer requirements.

Transcript

Dear students, Welcome to Gate Smashers. In this video, I am going to explain the difference between Verification and Validation. & I will use a real-life example to explain it, So that you will always remember this topic, whether in a university college exam or an interview, ask you anywhere. Although this topic is very simple. But sometimes stude... Read More

Key Insights

• Verification is the process of asking whether a product is being built correctly during every phase of development. Each partial product is checked before work advances, allowing developers to confirm that the current phase follows the specifications or artifacts established by the preceding phase.
• Validation is the process of asking whether the completed product is the right product. It happens after the full system has been prepared, when testers, a QA team, or the customer can evaluate the finished result against the agreed requirements.
• The SRS document is the principal reference used when validating the completed software. It records what the customer demanded and what the development side agreed to provide, so the finished product can be checked against those documented commitments.
• Developers are responsible for verification during the development phases. Like car manufacturers inspecting the chassis, tires, engine, and body as assembly progresses, developers check whether each software phase has been completed correctly before proceeding to the next one.
• Testers, the QA team, or the customer perform validation after the product is complete. Their task is to determine whether the finished system satisfies its intended requirements, rather than merely checking the correctness of an individual development phase.
• Phase containment of errors is a central concern of verification. Errors are identified within the phases where they are present and then removed, supporting the stated aim of making the final product error-free through repeated checks across development.
• Verification methods include reviews, inspections, walkthroughs, unit testing, and integration testing. Unit testing examines the smallest parts individually, while integration testing checks combined parts. Verification is mostly static because much of the work involves examination without executing the complete product.
• Validation is a dynamic activity because the completed system is executed and tested. In the car example, this means driving the finished vehicle in different environments and having different drivers operate it before the car is finally launched in the market.

Questions & Answers

Q: What is the difference between verification and validation?

Verification asks, "Are you building it right?" throughout the individual phases of development. Validation asks, "Have you built the right thing?" after the entire product is complete. Verification checks partial products and their relationship to earlier specifications, while validation tests the completed system against the SRS document and the customer requirements recorded there.

Q: When are verification and validation performed?

Verification is performed repeatedly during every phase of software development. After completing a phase, the developers check whether the work has been done correctly and conforms to the preceding artifact or specification. Validation is performed when the complete software is ready, allowing testers, the QA team, or the customer to assess the finished product as a whole.

Q: Who performs verification and who performs validation?

Developers perform verification while they build the software because they can inspect the output of each development phase and determine whether it was produced correctly. Validation is performed after completion by testers, a separate QA team, or finally the customer. These participants evaluate whether the finished product is the right product and meets the documented requirements.

Q: How is the SRS document used during validation?

The SRS document is used as the reference for checking the completed software during validation. It contains what the customer demanded and what the development side agreed to provide, with those commitments legally signed. Once the product is ready, validators compare it with the SRS to determine whether the agreed work has been completed correctly.

Q: What methods are used for software verification?

Verification uses reviews, inspections, walkthroughs, unit testing, and integration testing. Reviews, inspections, and walkthroughs examine work without necessarily running the complete system. Unit testing checks the smallest parts one by one, while integration testing checks parts after they have been combined. Together, these methods help identify errors during the relevant development phases.

Q: Why is verification considered mostly a static activity?

Verification is considered mostly static because much of it involves reviewing and inspecting work without executing the complete product. In the car example, the vehicle is still being assembled, so workers inspect elements such as nuts and bolts rather than driving it. Verification can include both static and dynamic activities, but the explanation characterizes it as mostly static.

Q: Why is validation considered a dynamic activity?

Validation is considered dynamic because it involves running and testing the complete product. For software, this means checking the finished system after it is ready. In the car example, validators drive the completed vehicle, operate it in different environments, and allow different drivers to test it before the car is finally launched in the market.

Q: How does the car manufacturing example explain verification and validation?

The car example divides manufacturing into phases involving the chassis and tires, engine, body, and final painting, interiors, and design. Checking the work after each phase represents verification because the manufacturer asks whether the car is being built correctly. Driving and testing the fully completed car before market launch represents validation because the finished product is evaluated.

Summary & Key Takeaways

• Verification occurs throughout software development, with developers checking each phase and its partial product against the specifications or artifacts established previously. The recurring question is whether the product is being built correctly. Detecting and removing errors within their originating phases supports the goal of producing an error-free final product.

• Validation occurs when the complete software product is ready. Testers, a QA team, or the customer examine whether the right product was built and whether it matches the SRS document. The SRS records what the customer demanded and what the development side agreed to provide, making it the basis for this final check.

• A car manufacturing example illustrates the distinction. Tires and the chassis, engine, body, paint, interiors, and design are checked as work progresses, representing verification. Once the finished car is ready for market, it is driven by different drivers and in different environments, representing the dynamic activity of validation.