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Explain V model with diagram

V-model means verification and validation model. It is sequential path of execution of processes. Each phase must be completed before the next phase begins. Under V-model, the corresponding testing phase of the development phase is planned in parallel. So there is verification on one side of V & validation phase on the other side of V.

Verification Phase:

1. Overall Business Requirement: In this first phase of the development cycle, the product requirements are understood from customer perspective. This phase involves detailed communication with the customer to understand his expectations and exact requirements. The acceptance test design planning is done at this stage as business requirements can be used as an input for acceptance testing.

2. Software Requirement: Once the product requirements are clearly known, the system can be designed. The system design comprises of understanding & detailing the complete hardware, software & communication set up for the product under development. System test plan is designed based on system design. Doing this at earlier stage leaves more time for actual test execution later.

3. High level design: High level specification are understood & designed in this phase. Usually more than one technical approach is proposed & based on the technical & financial feasibility, the final decision is taken. System design is broken down further into modules taking up different functionality.

4. Low level design: In this phase the detailed integral design for all the system modules is specified. It is important that the design is compatible with the other modules in the system & other external system. Components tests can be designed at this stage based on the internal module design,

5. Coding: The actual coding of the system modules designed in the design phase is taken up in the coding phase. The base suitable programming language is decided base on requirements. Coding is done based on the coding guidelines & standards.

Validation:

• Unit Testing: Unit testing designed in coding are executed on the code during this validation phase. This helps to eliminate bugs at an early stage.

• Components testing: This is associated with module design helps to eliminate defects in individual modules.

• Integration Testing: It is associated with high level design phase & it is performed to test the coexistence & communication of the internal modules within the system

• System Testing: It is associated with system design phase. It checks the entire system functionality & the communication of the system under development with external systems. Most of the software & hardware compatibility issues can be uncovered using system test execution.

• Acceptance Testing: It is associated with overall & involves testing the product in user environment. These tests uncover the compatibility issues with the other systems available in the user environment. It also uncovers the nonfunctional issues such as load & performance defects in the actual user environment.

  

Advantages of V-model:

• Simple and easy to use.

• Testing activities like planning, test designing happens well before coding.

• Saves a lot of time.

• Higher chance of success over the waterfall model.

• Proactive defect tracking – that is defects are found at early stage.

• Avoids the downward flow of the defects.

• Works well for small projects where requirements are easily understood.

Disadvantages of V-model:

• Very rigid and least flexible.

• Software is developed during the implementation phase, so no early prototypes of the software are produced.

• If any changes happen in midway, then the test documents along with requirement documents has to be updated.

When to use the V-model:

• The V-shaped model should be used for small to medium sized projects where requirements are clearly defined and fixed.

• The V-Shaped model should be chosen when ample technical resources are available with needed technical expertise.