For this what we do is we analyse the past experiences and the best practices are codified and this is converted as a knowledge. This is what is made used of, in building of the programs. So you are conscious from the very beginning what type of mistakes were committed and how to avoid them.
Making use of this knowledge, we design a product from the very beginning, that means from the very early stage, we start applying this sort of techniques, say when we try to look at user needs the other requirements, then the desired specifications that go through the design, then development of the programs are implemented, through all of these phases.
We try to make use of our knowledge, general knowledge, about how to avoid the errors. So, sort of a technique, the prevention model technique results in early design of test cases.
So the test cases are designed for every stage from the very beginning.
At the bottom what you see is and one extreme we have the demonstration model, which is a very simple model, and other one is your prevention model. There is a gradual transition from the demonstration model to the prevention model in our software practices.
