Various Life Cycle Models

The way you approach a particular application for testing greatly depends on the life cycle model it follows. This is because, each life cycle model places emphasis on different aspects of the software i.e. certain models provide good scope and time for testing whereas some others don’t. So, the number of test cases developed, features covered, time spent on each issue depends on the life cycle model the application follows.

No matter what the life cycle model is, every application undergoes the same phases described above as its life cycle.

Following are a few software life cycle models, their advantages and disadvantages.

Waterfall Model

Strengths:
•Emphasizes completion of one phase before moving on
•Emphasises early planning, customer input, and design
•Emphasises testing as an integral part of the life cycle •Provides quality gates at each life cycle phase

Weakness:
•Depends on capturing and freezing requirements early in the life cycle
•Depends on separating requirements from design
•Feedback is only from testing phase to any previous stage
•Not feasible in some organizations
•Emphasises products rather than processes

Prototyping Model

Strengths:
•Requirements can be set earlier and more reliably
•Requirements can be communicated more clearly and completelybetween developers and clients
•Requirements and design options can be investigated quickly and with low cost
•More requirements and design faults are caught early

Weakness:
•Requires a prototyping tool and expertise in using it – a cost for the development organisation
•The prototype may become the production system

Spiral Model

Strengths:
•It promotes reuse of existing software in early stages of development
•Allows quality objectives to be formulated during development
•Provides preparation for eventual evolution of the software product
•Eliminates errors and unattractive alternatives early.
•It balances resource expenditure.
•Doesn’t involve separate approaches for software development and software maintenance.
•Provides a viable framework for integrated Hardware-software system development.

Weakness:
•This process needs or usually associated with Rapid Application Development, which is very difficult practically.
•The process is more difficult to manage and needs a very different approach as opposed to the waterfall model (Waterfall model has management techniques like GANTT charts to assess)