First of all I'd like to discuss why V-model was designed if we already had Waterfall model in place.
The waterfall was sequential model and the testing was covered at the last phase of the product. So the defect caught at last phase of the the development incurs more cost than in the beginning phase.
V - Model is an extension of the waterfall model and is based on association of a testing phase for each corresponding development stage.. So this model allowed us to catch the defects at early stage of development. In this model development and testing activities were done side by side.
V- Model Diagram
Verification Phases :
Requirements analysis : It is the first phase of the verification process . This is the first phase in the development cycle where the product requirements are understood from the customer perspective. This phase involves detailed communication with the customer to understand his expectations and exact requirement. This is a very important activity and need to be managed well, as most of the customers are not sure about what exactly they need. The acceptance test design planning is done at this stage as business requirements can be used as an input for acceptance testing.
The high-level design (HLD)(System Design): Once you have the clear and detailed product requirements, it.s time to design the complete system. System design would comprise of understanding and detailing the complete hardware and communication setup for the product under development. System test plan is developed based on the system design. Doing this at an earlier stage leaves more time for actual test execution later.
The low-level design (LLD)(Architecture design) phase is where the actual software components are designed. It defines the actual logic for each and every component of the system. Class diagram with all the methods and relation between classes comes under LLD. Component tests are created in this phase as well.The data transfer and communication between the internal modules and with the outside world (other systems) is clearly understood and defined in this stage. With this information, integration tests can be designed and documented during this stage.
The implementation phase(Module design) : In this phase the detailed internal design for all the system modules is specified, referred to as Low Level Design (LLD). It is important that the design is compatible with the other modules in the system architecture and the other external systems. Unit tests are an essential part of any development process and helps eliminate the maximum faults and errors at a very early stage. Unit tests can be designed at this stage based on the internal module designs.
Coding: The actual coding of the system modules designed in the design phase is taken up in the Coding phase. The best suitable programming language is decided based on the system and architectural requirements. The coding is performed based on the coding guidelines and standards. The code goes through numerous code reviews and is optimized for best performance before the final build is checked into the repository.
Validation Phases
Following are the Validation phases in V-Model:
Unit Testing: Unit tests designed in the module design phase are executed on the code during this validation phase. Unit testing is the testing at code level and helps eliminate bugs at an early stage, though all defects cannot be uncovered by unit testing.
Integration Testing: Integration testing is associated with the architectural design phase. Integration tests are performed to test the coexistence and communication of the internal modules within the system.
System Testing: System testing is directly associated with the System design phase. System tests check the entire system functionality and the communication of the system under development with external systems. Most of the software and hardware compatibility issues can be uncovered during system test execution.
Acceptance Testing: Acceptance testing is associated with the business requirement analysis phase and involves testing the product in user environment. Acceptance tests uncover the compatibility issues with the other systems available in the user environment. It also discovers the non functional issues such as load and 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. This
saves a lot of time. Hence higher chance of
success over the waterfall model.
-Easy to manage due to the rigidity of the model . each phase has specific deliverables and a review process.
-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.
-Poor model for long and ongoing projects.
-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.
-No working software is produced until late during the life cycle.
The waterfall was sequential model and the testing was covered at the last phase of the product. So the defect caught at last phase of the the development incurs more cost than in the beginning phase.
V - Model is an extension of the waterfall model and is based on association of a testing phase for each corresponding development stage.. So this model allowed us to catch the defects at early stage of development. In this model development and testing activities were done side by side.
V- Model Diagram
Verification Phases :
Requirements analysis : It is the first phase of the verification process . This is the first phase in the development cycle where the product requirements are understood from the customer perspective. This phase involves detailed communication with the customer to understand his expectations and exact requirement. This is a very important activity and need to be managed well, as most of the customers are not sure about what exactly they need. The acceptance test design planning is done at this stage as business requirements can be used as an input for acceptance testing.
The high-level design (HLD)(System Design): Once you have the clear and detailed product requirements, it.s time to design the complete system. System design would comprise of understanding and detailing the complete hardware and communication setup for the product under development. System test plan is developed based on the system design. Doing this at an earlier stage leaves more time for actual test execution later.
The low-level design (LLD)(Architecture design) phase is where the actual software components are designed. It defines the actual logic for each and every component of the system. Class diagram with all the methods and relation between classes comes under LLD. Component tests are created in this phase as well.The data transfer and communication between the internal modules and with the outside world (other systems) is clearly understood and defined in this stage. With this information, integration tests can be designed and documented during this stage.
The implementation phase(Module design) : In this phase the detailed internal design for all the system modules is specified, referred to as Low Level Design (LLD). It is important that the design is compatible with the other modules in the system architecture and the other external systems. Unit tests are an essential part of any development process and helps eliminate the maximum faults and errors at a very early stage. Unit tests can be designed at this stage based on the internal module designs.
Coding: The actual coding of the system modules designed in the design phase is taken up in the Coding phase. The best suitable programming language is decided based on the system and architectural requirements. The coding is performed based on the coding guidelines and standards. The code goes through numerous code reviews and is optimized for best performance before the final build is checked into the repository.
Validation Phases
Following are the Validation phases in V-Model:
Unit Testing: Unit tests designed in the module design phase are executed on the code during this validation phase. Unit testing is the testing at code level and helps eliminate bugs at an early stage, though all defects cannot be uncovered by unit testing.
Integration Testing: Integration testing is associated with the architectural design phase. Integration tests are performed to test the coexistence and communication of the internal modules within the system.
System Testing: System testing is directly associated with the System design phase. System tests check the entire system functionality and the communication of the system under development with external systems. Most of the software and hardware compatibility issues can be uncovered during system test execution.
Acceptance Testing: Acceptance testing is associated with the business requirement analysis phase and involves testing the product in user environment. Acceptance tests uncover the compatibility issues with the other systems available in the user environment. It also discovers the non functional issues such as load and 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. This
saves a lot of time. Hence higher chance of
success over the waterfall model.
-Easy to manage due to the rigidity of the model . each phase has specific deliverables and a review process.
-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.
-Poor model for long and ongoing projects.
-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.
-No working software is produced until late during the life cycle.
No comments:
Post a Comment