Verification and Validation in Testing

Introduction

You are at the right place! This is not a free vocabulary-building class but a critical evaluation of a much sought-after debate around verification and validation in the software testing world. Why do we need to know the difference between Verification and Validation? Even though they sound just about the same, they carry different meanings depending on what you intend to do as a tester/developer in the software development and testing process. They both go hand in hand while solving a problem. However, there is a lot of confusion around the meaning of these two words concerning software testing. While there may be many definitions of these terms in various fields on the internet, here we will look at these terms in the testing space and analyze both of these terms in detail.

Verification vs Validation

Software testing is a vast field. It involves various methods and processes proposed to solve different software testing issues. Verification and Validation are also a part of the same group in software testing. It is also known as a V-Model (Verification and Validation model) in the context of software development and testing.

What Is Verification?

Software Engineering standard IEEE-STD-610defines verification as:

“A system test to prove that it meets all its specified requirements at a particular stage of its development.”

Let’s try and understand this definition. The application building process starts with verifying a set of outlined specifications. So, verification ensures that all the specifications are taken care of before the development of the application starts.
In simple terms, Verification is all about testing whether your software product satisfies the conditions you specified in the initial stages of development. It includes all actions taken to build the desired software product, like going through the specification documents, ensuring it complies with the code logic, checking code reviews, doing narrow inspections, design analysis, walk-through, static testing, etc. Verification is more of an internal process accomplished when the product is still under development, unlike Validation, which is performed after the completion of the product. The verification process eliminates bugs at the beginning stages of development to ensure the product’s reliability. Verification analyzes the complete design of the application in a predictive way. This analysis serves as the basis for the successful working of the Input/Output functions once the development is complete. It also analyzes how accurate and qualified the product design is. Unit Testing and System testing are preferably performed to verify if the software code follows the unit specifications and if the modules connect as a complete system.

What Is Validation?

Now let’s understand the definition of Validation through IEEE-STD-610:

“An activity that ensures that an end product stakeholder’s true needs and expectations are met.”

The validation process is performed once a part of the product or the entire application is built. Validation ensures that the necessary steps are taken to make the product as planned. Validation is generally carried out using regression, user, performance, and others, user testing, performance testing, etc. Validation-related issues occur when there is improper or lack of communication between the user and the problem solver (developer). This is why developers must use validation to check if the built product covers the user needs and their acceptance of the product and ensures the proper functioning of the whole system to fulfill these needs. Usually, various companies undergo acceptance testing by demonstrating their software product to the end-user and getting their feedback to check how well they accept the outcome.

Verificatiion and Validation comparison

Figure 1 Comparison of Verification and Validation

Verification and validation are the two keywords used in software testing. Sometimes they are used interchangeably, but they are different from each other. Both the terms are a part of the V&V model (Verification and Validity), and they try to achieve two main tasks:

  • Check the product from the developer’s point of view: It checks if the product complies with the requirement. It also shows what a developer thinks about the final product.
  • Check the product from the consumer’s point of view: It checks if the product befits the customer’s use. It contains how a consumer looks at the final product.

The difference between verification and validation is mainly in terms of the specifications’ role. The validation process is to verify if the software product captures the customer’s needs as intended or adheres to the pre-defined specifications; verification ensures that the product is well-engineered to meet the specifications responsibly or whether the product is built right or not. Validation scrutinizes the proposed system to check its ability to fulfill real-world needs.
The debate around verification vs. validation is ever prevailing. So, let’s have a closer look at the difference between Verification and Validation with the help of a comparison chart:

Key Points of Difference VERIFICATION VALIDATION
Question it answers Was I able to build the right product? Was I able to make what was needed and in the right way?
Definition It is the process of system/software product evaluation at different development phases to figure out if it matches the specifications It is a process in which a system/software product is evaluated at the end of the development cycle to ensure if it is built to meet the requirements of the end-users or not
Objective To ensure the product is developed as per specified requirements and designs. If it deviates from the specifications, take corrective measures at the first stage of development itself Checking to ensure that the product is developed correctly, as per user requirements. If it does not meet the requirements, then it should be re-built/tweaked until it meets the level of acceptance by the user
Coding Requirement Does not require code execution Requires code execution
Method Type It is a static method in which all first stage documentation and file regarding the product is verified, and no/ minimum coding is involved in this process It is a dynamic method in which the actual product is directly tested at its different build phases. It is also dynamic because it involves the execution of code
Activities The verification process includes activities like planning, walk-through, Inspection, reviews of product development and specifications, desk-evaluation, etc. Validation involves activities like Black Box Testing, White Box Testing, Non-Functional Testing, and many more to ensure an error-free product is delivered to the customer and that the product matches the specifications
Degree of Activity Involves Low level activities Involves High Level activities
Targets Software Application, specifications, Design, Architecture Actual Built Product
Performer Verification is carried out by the software testers Validation requires both Software Developers who execute the and software testers who assist the developers wherever required
Execution Order Verification/Quality Assurance is performed before validation at the initial phase of development Validation/Quality Control follows after the verification towards the end of the software development
Orientation Verification is process oriented Validation is product oriented
Cost Involved Low Cost involved High Cost involved
Error Detection stage It can detect errors right at the beginning stage of development It detects errors only after the product is built
Characteristics Early stage error discovery, accurate and speedy verification, etc. Robustness, precision, inclusiveness, etc.
Human Intervention It is mainly performed manually It involves coding and program execution which actively needs the computer system intervention. Still, at the same time, the program is written by a human being. Hence, it involves both humans and machines
Internal/ Internal Verification is an internal process of development, and production Validation is an external process that requires a stakeholder acceptance of the built product.

Figure 2 Comparison Chart

When To Use Verification and Validation?

The difference between Verification and Validation might have given us an overview of how different they are regarding performance. But it is also worth noting that both the processes need to be performed together to get the maximum clarity on how well the application conforms to the specifications laid down during the initial development stages. Functioning together ensures that it has achieved what was intended and makes an essential pair of components for quality management.

Your software product may clear the verification process. Still, it fails to pass the validation phase, which means that the product might have met all the specifications and requirements planned at the verification stage. However, the specifications were not strong enough to meet the end user’s requirements. Hence, both of them are essential to provide a 360-degree quality overview.

Conclusion

The words Verification and Validation are often used interchangeably, but the terms are different in many ways. To summarize the Verification vs. Validation debate and make it simpler. Note that the former mainly involves verifying and reviewing activities that will lead to building the intended software. The latter consists in performing actual testing activities responsible for developing the right product. Even though there is a difference between verification and validation, they complete each other. They should be performed together to gain insights into the overall quality of the product.

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