V Model

The V-model was developed to address some of the problems experienced using the traditional waterfall approach. Defects were being found too late in the life cycle, as testing was not involved until the end of the project. Testing also added lead time due to its late involvement. 

The V-model provides guidance that testing needs to begin as early as possible in the life cycle.The V-model is a model that illustrates how testing activities (verification and validation) can be integrated into each phase of the life cycle. Within the V-model, validation testing takes place especially during the early stages and the later stages of the life cycle.

Although variants of the V-model exist, a common type of V-model uses four (04) test levels. 

The four test levels used, each with their own objectives, are:

• component testing: searches for defects in and verifies the functioning of software components (e.g. modules, programs, objects, classes etc.) that are separately testable

•  integration testing: tests interfaces between components, interactions to different parts of a system such as an operating system, file system and hard ware or interfaces between systems

• system testing: concerned with the behavior of the whole system/product as defined by the scope of a development project or product. The main focus of system testing is verification against specified requirements

• acceptance testing: validation testing with respect to user needs, requirements, and business processes conducted to determine whether or not to accept the system

 Figure 1: VModel