Which model integrates testing design with all life cycle stages, starting at the requirements analysis stage?

The model that integrates testing design with all life cycle stages, beginning from the requirements analysis stage, is the Validation and Verification Model, commonly referred to as the V-model. This approach is characterized by its strong emphasis on the relationship between development and testing phases. In the V-model, for each development stage, there is a corresponding testing phase that ensures requirements are verified and validated at every step.

Starting with requirements analysis, the model visually represents the stages of development on one side and the associated testing stages on the other, forming a 'V' shape. This allows for early test planning and ensures that testing is not merely an afterthought but an integral part of the development process. It enhances product quality by identifying defects early on, which reduces the cost and time associated with later-stage fixes.

In contrast, other models may not emphasize testing at every phase as prominently. For instance, Agile Development focuses more on iterative development and flexibility, while the Spiral Method emphasizes risk management through iterative cycles. The Iterative Method allows for refinement and repeat testing but does not necessarily integrate testing from the very beginning of the life cycle stages in the structured manner that the V-model does. Therefore, the V-model's structured approach to integrating testing throughout the entire life cycle makes it the