V Model In Software Engineering

V Model In Software Engineering: The V Model is a popular structured method for developing software. It outlines a clear step-by-step process for building high-quality software programs. The V Model gets its name from the V shape formed by its stages.

The stages in defining and building the software are on the left side of the V. On the right side are the testing stages that parallel each build stage. Following the steps on both sides of the V ensures the software is thoroughly reviewed and tested.

Using the V Model helps software teams be efficient, write better code, and reduce risks. It guides teams through important tasks like gathering requirements, designing and implementing the software, testing it at each phase, and maintaining it. The V Model provides a systematic framework for the entire software development life cycle.

V Model Testing in SDLC

In the v model, the process is executed in v-shape. In the V-model, each development phase is directly associated with the respective test phase. Because of this, the next phase is started only after the completion of the previous phase.

This V model is also known as the verification and validation model. so, to better understand the v model, let’s get some idea about it.

What is Verification?

The process of evaluating a drug development phase’s document/ work product is called verification. The verification is also called static testing because, during the verification of the software application, the real application is not executed or used. But we have verified the documents, and the codes find the defects.

Different verification methods are present to verify the documents or the codes of the application. That is:


Various Phases Of Verification

V Model Phases
V Model Phases

Requirement analysis: During this phase, all the requirements and expectations details are collected from the customer. This phase is called requirement gathering.

The client sends the Business Requirements Specification (BRS) at this stage. After receiving the BRS, developers translate that BRS to SRS, and testers are involved in reviewing the BRS, trying to find out the missing or wrong requirements, and writing an acceptance test plan and test cases.

System Design /High-Level Design: During this phase, a high-level design is built, and the team will discuss how those requirements can be implemented. the team will also come up with what can be created, the dependencies, and the software and hardware required to develop the product.

Architectural design: During this phase, the System design is divided into different functionalities. How the data will transfer between other internal modules and other systems is clearly understood.

In this phase, the development team will start preparing the product’s Low-level design (LLD), and the test team will be involved in reviewing the High-level design (HLD) and preparing the integration test plan and test cases.

Module Design: During this phase, the functionalities are again divided into small modules. This phase finalizes methods, classes, interfaces, and data types.

In the next phase, the development team will start writing coding for the product, and the test team will review the low-level design (LLD) and write functional or unit test plans and test cases.

What Is Validation?

The process of evaluating a software application during or at the end of the development phase is called validation. The validation is also dynamic testing. During the validation, we are using the real application to find out the defect in it.

During the validation process, we try to find out that the developed software product (development completed) meets the customer’s expectations and requirements. To find out the defects of the application, we are using different techniques or methods, which are:

Because of this nature in the v model, all verification phases are found on one side; on the other, you can see all validation phases. By joining both phases, it will look like a v-shape. That’s why it is called the V Model.

This V model starts with the business requirement on one hand, and the other side ends with the user acceptance testing.

Various Phases Of Validation

Unit Testing: Testers execute the unit test plan and test cases developed by the testers in the module design phase to find bugs in the unit or code level.

Integration Testing: during this phase, testers execute test plans or test cases after unit testing. During the testing, testers concentrate more on the communication data between modules.

System Testing: During system testing, testers test the complete application for functionality, interdependency, and communication. During this phase, testers test the functional and non-functional requirements of the developed application.

User acceptance testing (UAT): This testing is performed on the user environment, that is, in the production environment. In UAT testing, we verify that the developed product meets the user requirement and is ready to use in the real environment.

When To Use the V Model?

If you follow the V model, it is tough to return to the previous page once it is completed. If you are a software project that needs some flexibility, then it’s very rigid. But if you are more focused on quality, an essential aspect of the delivery, this model can be critical and suitable for you.

so, as compared to the Waterfall model, you can use this model on such a project where the requirements are not changing, for example:

  • The customer has precise documented requirements.
  • Military projects
  • Embedded systems
  • Such projects where the requirement is well defined and clear

Advantages Of V Model

  • In the V-Model, both development and testing happen in a very organized and systematic manner.
  • It is suitable for smaller and medium-sized projects.
  • Testing starts from the beginning, so if there are any defects, they can only be found in the early stage.
  • It’s easy to manage, and each phase has defined objectives and goals.

Disadvantages Of V Model

  • It is not suitable for big or complex projects.
  • It is unsuitable for projects whose requirements are unclear and inconsistent because the same process needs to be carried out whenever we expect some change, so we need more documentation.
  • the user will not be able to get any software in the intermediate stage.
  • The initial investment in the project will increase because of the testing team’s involvement.

Difference Between Verification and Validation

ObjectiveEnsure the product meets specified requirements and design specificationsEnsure the product meets user expectations and requirements
QuestionAre we building the system right?Are we building the right system?
ActivitiesReviews, inspections, meetingsTesting (black box, white box, etc.)
Performed ByQA teamTesting team
Execution of CodeNot involvedInvolved
StageBefore validationAfter verification
Items EvaluatedPlans, requirements, design documents, code, test casesActual software product
Cost of Finding DefectsLess than validationMore than verification
ChecksDocuments and specification files manuallySoftware system based on specs


The V Model excels in facilitating parallel validation and verification at each development stage, making it particularly effective for projects with well-defined and stable requirements. However, its suitability diminishes in the face of large, complex projects characterized by uncertain requirements. The inherent advantage lies in the assurance that each step is executed correctly, enabling focused bug identification without the need to revisit all prior stages when issues arise.

As you consider the right approach for your project, if simplicity and clear customer requirements align with your needs, the V Model emerges as a fitting choice. Your project’s success hinges on selecting the methodology that aligns with its unique characteristics and demands.

We value your insights! If you have any comments, suggestions, or experiences to share regarding the V Model or other software development methodologies, please feel free to contribute below. Your input is invaluable in our continuous efforts to enhance and refine our understanding of these methodologies.

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