Verification vs. Validation in Software Testing: Know the Basics

Verification and validation in software testing are the processes to check whether a software system fulfills its purpose and meets the specifications intended.

These two terms are also referred to as software quality control used by software testers in the software development life cycle. Although both look and sound similar, they differ in their analysis. 

Verification is the process of determining the software’s quality, whereas validation is checking the customer’s requirements through the software functionality. Validation is conducted after the verifications are completed at the end of the development cycle. 

Well, there is a lot of confusion around these terms in the application testing world. So, if your work relates to software testing or you are just curious about it, you need to know the differences between these terms in software testing. 

In this article, I’ll discuss verification and validation, their benefits, and more. Later I’ll describe the differences between these terms in a table. 

Here we go!

What Is Verification?

Verification is a simple process of verifying the software in the development process. It includes meetings, inspections, walk-throughs, reviews, and more in order to evaluate plans, codes, documents, specifications, and requirements. 

In its technical term, it is defined as the process that involves evaluating the application to determine whether it meets the requirements and can satisfy the customers or end users.

Thus, the primary purpose of verification is to ensure software application quality, architecture, design, and more. In verification, specifications act as the inputs for the application development process. The code is written based on the documents that specify the specifications in detail. 

The software testers use various verification methods depending on the application’s scope and complexity. Sometimes, they use mathematical models and derived calculations to make predictions about the software and verify the logic behind the code. 

Furthermore, verification checks whether the development team builds the product right. In other words, verification is a process that starts in advance of the validation process and continues until the software is validated and released. 

There are three phases involved in the verification process. They are:

• Requirements verification: It is a process to verify and confirm that the demands or requirements are complete, correct, and precise. Before the application goes for design, the software testing team verifies the customer or business requirements for their completeness and correctness. 
• Design verification: It is a process to check if the software application meets the design specifications mentioned in the document by providing evidence. Here, the software testing team checks the prototypes, layouts, architectural design, logical database models, and navigational charts of the application to meet the targeted functional as well as non-functional requirements. 
• Code verification: It is a process to check the code for its correctness, consistency, and completeness. In this process, the software testing team checks whether the construction artifacts, including user interfaces, source codes, and physical database models, meet the design specification. 

Let’s take a real-life example to understand this concept.

When you hire an interior designer for your home, you first need to tell your requirement. According to those requirements, the interior designer team develops a model to show you how it looks. The same team also tests the feasibility of that design and makes changes according to the requirement and feedback to finalize the one that’s correct and meets the owner’s demand as well. 

Here, the house model is the code, interior design teams are the developers and testers, and the house owner is the customer. 

What Is Validation?

Validation is a process used to evaluate the software according to the business or customer demands during or at the end of the software development process. It evaluates the final application to check whether the application meets the expectations and requirements of customers. 

It is known as the dynamic mechanism of validating the actual project along with testing. Validation focuses on the output; it doesn’t have anything to do with internal processes. It is a one-time process that starts only after the verification process. 

Software teams use various validation methods, such as black box testing (functional testing) and white box testing (non-functional testing or design/architectural testing). 

• White box testing helps in validating the application through predefined series of data inputs. Thus, testers compare the output of the software application values against the input data values to check if the software is producing similar output as expected. 
• In black box testing, there are three important variables – input values, expected output values, and output values.

In short, functional testing or black box testing includes integration testing, system testing, and unit testing, whereas non-functional testing or white box testing includes user acceptance testing. 

Validation ensures you’ve developed the software product right by checking the software content according to the customer specifications. 

Validation processes encompass the following steps:

• Design review: The software testing team outlines the requirements of customers. Later, they create a testing plan to confirm each item in the software before going for production. Development teams will receive approval regarding the readiness of the product.
• Installation review: The software testing team attempts installation of the software application according to the testing plan. The purpose is to make sure the installation process and the essential system hardware adhere to the specifications. Moreover, testers confirm the status of the software functions. 
• Operational review: Software testers put the application through different testing scenarios to check its completeness. The goal is to review all the operations or functionality to determine if the software works as the customer has requested. 
• Performance review: It shows that the software application can function according to the business needs in real-world conditions. Clients can also conduct beta testing to get a feel and know whether it’s been developed correctly. An external set of views spot defects and bugs clearly which might have been missed by the developed team.
• Production readiness review: Once all the reviews are completed, the validation process is complete, and the product is moved to production-ready. This means the team can move ahead with releasing the application to the production environment. 

Furthermore, if defects and bugs are discovered after the release, the software development team can release new updates to address these issues. 

Let’s take the previous example and understand what validation is.

For the team working on an interior designing project, verification will help you produce the final result of your complete home interior finishing. But, validation is the next step that can be tested by feeling and analyzing that design. Validation comes when you find your house the same as you saw in the design.

Another example is supposed you want to have pancakes from a given cafe. To validate that the pancake is the same pancake you ordered, you need to taste it.

Verification vs. Validation: Benefits

Benefits of Verification

Let’s discuss some advantages of verification testing:

• Frequent and early verification reduces the risk of software failure and helps in minimizing the defects and bugs that may show up later. 
• Stakeholders, product managers, and developers get more insights into the software application by verifying the codes at each stage. This way, they can predict how the software will perform in the later stages. 
• Verification of the software helps keep your software aligned with business and customer requirements at each stage of the development phase. This helps devs to put less unnecessary work as the development continues. 
• Since all the bugs can’t be fully eliminated, verification helps QAs estimate the issues that might show up later so that they can prepare a document to immediately handle those bugs at the time of need. 
• It reduces the cost of reprinting and reshipping.
• In verification, the chance of system failures after the development phase is lower. 

Benefits of Validation

All validation tests are performed to ensure that the system works as expected by running its functions and tracking quantifiable and tangible results. 

Let’s discuss the advantages of validation in software testing.

• Any defects or bugs missed during the verification stages can be easily detected while running all the validating tests. 
• If specifications are inadequate or not correct from the beginning, validation reveals their inefficacy. This will prevent the bad software application from hitting the market.
• Validation tests confirm that the software application matches and adheres to the business or customer demands, expectations, and preferences under a variety of conditions, such as low battery, slow connectivity, and more.  
• These tests allow the software to function across various browser-device-OS combinations. This means validation authenticates software for cross-browser compatibility. 
• Validation helps improve the reliability of the software application. 

Verification vs. Validation: When to Use Them?

When to Use Verification Testing?

Verification tests run at every stage of the development cycle before implementing any feature. 

For example, add a button labeled “Add to Wishlist” to your website. Before starting with the creation of the button, verification tests look into the requirements that are previously decided in the brainstorming and ideation phases. 

Let’s say, in the documentation, it is mentioned that the button must be blue with the letters written in magenta, and it shouldn’t be larger than 15mm X 10mm. Also, the button should be constantly visible in the below middle of every product page of the site. 

Another button of the same feature should be placed under each product on the page. Before starting the work, the requirements and design table must be reviewed, and the necessary specifications must be listed. 

In short, verification testing is used before and during the development cycle of the software application. 

When to Use Validating Testing?

The validation process runs after each step or feature in the development cycle is completed. For example, unit tests are run after every unit of code is created. Similarly, integration tests are run after different modules are completed individually and ready for combination. 

Cross-browser testing, a form of validation testing, is an important element in validation. QA teams must check that every feature, design element, and function appears as expected on different browser-device-OS combinations. For example, QAs need to check if the “Add to Cart” button shows up in every browser and functions properly on any device browser. 

Software testers work on the product to ensure that the software’s output is correct by using validation methods like white box testing (which goes over internal application code) and black box testing (or, behavioral testing, which looks only for external functions of the applications). 

Now, let’s discuss the main differences between verification and validation.

Verification vs. Validation in Software Testing: Differences

Verification: Are we developing the product correctly?

Validation: Are we developing the correct product that meets the customer’s requirements?

Verification and validation are integral parts of software development. Without proper verification and validation, a software team can’t build a quality product. These terms help in minimizing the risks of product failure and improve the reliability of the software application. 

Both have different uses in different software development and project management firms. For instance, both happen simultaneously in the agile development methodology since there is a need for both in continuing business processes. 

Here are the key differences between verification and validation in the below table:

Verification and Validation (V&V) in Different Phases of Software Development Cycle

Verification and validation are performed at every stage of the development process. Let’s have a look:

• The planning phase involves verification of the contract, evaluation of the concept document, and performing risk analysis.
• The requirement phase includes evaluation of the software requirements and interfaces and generation of acceptance and systems test plan. 
• The design phase includes the evaluation of software design and interfaces and the generation of the integration plan, test design, and component test plan. 
• The implementation phase includes the evaluation of source code and documents, the generation of test cases and procedures, and the execution of component test cases. 
• The test phase includes execution of system and acceptance test cases, updating traceability metrics, and risk analysis. 
• The installation and checkout phase involves an audit of configuration and installation, a final test of installation, and the generation of a final test report. 
• The operation phase involves the evaluation of new constraints and the assessment of the proposed change. 
• The maintenance phase includes evaluation of the anomalies, assessment of migration and retrial features, proposed changes, and validation of the production issues. 

Conclusion

Verification and validation processes are essential aspects of software development. These processes can help you determine whether the software application is made as per the requirements defined, conforms to the business needs, and can satisfy customer demands.

Both processes might look similar but are different in terms of how they are implemented during the software development lifecycle.

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