Now, let us look at the models of the test. There are the first two models, called the demonstration model, and the destruction model. These two really are called phase wise models, because the testing is done as a phase of a development phase. These models view testing at the end of the development cycle and so they are called phase wise models. The other two models, the evaluation model and the prevention model, are the life-cycle models. The process of testing is in the form of evaluation and this will be occurring from the very beginning till the end. The prevention model is a little bit different. It has to prevent. It takes all the steps to ensure that we prevent the faults getting into the program. So, this is what I call life-cycle models, because the prevention is something which will be doing all the cycle, all the phases.

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