The V Model is an extension of Waterfall Model. In Waterfall model all the process we do in linear fashion, but in V-model after coding the process steps are bent upwards to form a V-Shape. as shown in below diagram

Process in V Model:

  • As soon as requirements are given in the form of BRS both Developers and Test Engineers are hired.
  • Test engineers will review the BRS document and write the User Acceptance test document.
  • Simultaneously BRS will be converted into SRS by BA.
  • Once it is completed Test Engineers will review the SRS and prepare System Test document.
  • Simultaneously SRS will be converted into HLD (High Level Design).
  • After this Test Engineers will review the HLD and prepare Integration Test document.
  • Simultaneously HLD will be converted into LLD (Low Level Design)
  • Once LLD is designed Test Engineers will review the LLD and prepare Functional Test Document.
  • Developers starts writing the Code in one of the programming language.
  • Once coding is completed they do one round of Unit Testing and hand over the application to  test engineers.
  • Now the TE will start Functional Testing by using Functional Test Documents.
  • After functional testing they do Integration Testing by making use of Integration Test documents.
  • After Integration testing test engineers will do System Testing by making use of System Test documents.
  • Once system testing is done they are going to deploy the application to the customer.
  • The customer will do one round of User Acceptance testing by making use of User Acceptance test documents.

Below are few questions generally asked in interviews regarding the V-Model

Q) Why Test Engineers will review the requirements?

Ans: In order to find the conflict requirements and missing requirements.

Q)Why it is called V model?

Ans: Since entire process takes place in V shape ie., First we review and prepare test documents and at a point when the coding is completed we go back and start reusing the test documents for Testing.

Q) Why V & V model?

Ans: Since execution happens in two steps ie., Entire verification takes place and once coding is completed the validation process starts hence it is called Verification and Validation model.

Q) When we are going to use V model?

Ans: We are going to use V model for large and complex applications.


  • Review exists at each and every stage.
  • Parallel deliverables exists ie., two phases will be working at the same time.
  • Test Engineer will have more product knowledge since he is involved from the beginning.
  • Robust product is delivered.
  • Test documents can be reused.


  • Time consuming if requirement changes since they have to make change in the test documents.
  • Costlier approach.

In the next post we will see about Hybrid Model ….