V-model (software development)
The V-model is a software development model which can be presumed to be the extension of the waterfall model. Instead of moving down in a linear way, the process steps are bent upwards after the coding phase, to form the typical V shape. The V-Model demonstrates the relationships between each phase of the development life cycle and its associated phase of testing.
Evolution
The V-model can be said to have developed as a result of the evolution of software testing. Various testing techniques were defined and various kinds of testing were clearly separated from each other which led to waterfall model evolving into the V-model. The tests in the ascending (Validation)hand are derived directly from their design or requirements counterparts in the descending (Verification) hand. The ‘V’ can also stand for the terms Verification and Validation.
Verification Phases
Requirements analysis
Main article Requirement See also Functional requirements See also Non-functional requirements
In this phase, the requirements of the proposed system are collected by analyzing the needs of the user(s). This phase is concerned about establishing what the ideal system has to perform. However, it does not determine how the software will be designed or built. Usually, the users are interviewed and a document called the user requirements document is generated.
The user requirements document will typically describe the system’s functional, physical, interface, performance, data, security requirements etc as expected by the user. It is one which the business analysts use to communicate their understanding of the system back to the users. The users carefully review this document as this document would serve as the guideline for the system designers in the system design phase. The user acceptance tests are designed in this phase.
System Design
Main article Systems design
System engineers analyze and understand the business of the proposed system by studying the user requirements document. They figure out possibilities and techniques by which the user requirements can be implemented. If any of the requirements is not feasible, the user is intimidated about the issue. A resolution is found and the user requirement document is edited accordingly.
The software specification document which serves as a blueprint for the development phase is generated. This document contains the general system organization, menu structures, data structures etc. It may also hold examples business scenarios, sample windows, reports for the better understanding. Other technical documentation like entity diagrams, data dictionary will also be produced in this phase. The documents for system testing is prepared in this phase.
Architecture Design
See also Computer architecture, Software architecture
This phase can also be called as high-level design. The baseline in selecting the architecture is that it should realize all the requirements within the given time, cost and resources. Software architecture is commonly represented as two-tier, three-tier or multi-tier models which typically comprises of the database layer, user-interface layer and the application layer. The modules and components representing each layer, their inter-relationships, subsystems, operating environment and interfaces are laid out in detail.
The output of this phase is the high-level design document which typically consists of the list of modules, brief functionality of each module, their interface relationships, dependencies, database tables, architecture diagrams, technology details etc. The integration testing design is carried out in this phase.
Module Design
See also Modularity (programming)
This phase can also be called as low-level design. The designed system is broken up in to smaller units or modules and each of them is explained so that the programmer can start coding directly. The low level design document or program specifications will contain a detailed functional logic of the module, in pseudocode - database tables, with all elements, including their type and size - all interface details with complete API references- all dependency issues- error message listings- complete input and outputs for a module. The unit test design is developed in this stage.
Coding
Refer Coding
Validation Phases
Unit Testing
Main article Unit Testing
Integration Testing
Main article Integration testing
System Testing
Main article System testing
User Acceptance Testing
Main article Acceptance testing