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#Software architecture notes 7th sem vtu result software

Tests should be properly designed and tested before applying it to the acutal code.

#Software architecture notes 7th sem vtu result software

Test Design: We know that the software code must be designed and tested, but many appear to be unaware that tests themselves must be designed and tested.

Identifying the testing techniques to test the code is the main key here. Testable code has fewer bugs than the code that's hard to test. Other reason is to check the testable and non-testable code. One reason is to reduce the labour of testing.

Phase 4: (1988-2000: Prevention Oriented) Testability is the factor considered here.

(Note: This is applied to large software products with millions of code and years of use.) The product is released when the confidence on that product is high enough. Notion is that testing does improve the product to the extent that testing catches bugs and to the extent that those bugs are fixed.

Phase 3: (1983-1987: Evaluation Oriented) The purpose of testing is not to prove anything but to reduce the perceived risk of not working to an acceptable value (Statistical Quality Control).

Also, a bug corrected may also lead to another bug. This also failed because the software will never get released as you will find one bug or the other.

Phase 2: (1979-1982: Destruction Oriented) The purpose of testing is to show that software doesnt work.

The more you test, the more likely you'ill find a bug. This failed because the probability of showing that software works 'decreases' as testing increases.

Phase 1: (1957-1978: Demonstration Oriented) The purpose of testing here is to show that software works.Phase 0 thinking was the norm in early days of software development till testing emerged as a discipline. Phase 0: (Until 1956: Debugging Oriented) There is no difference between testing and debugging.Phases in a tester's mental life can be categorised into the following 5 phases:.A prevented bug is better than a detected and corrected bug. Testing and Test Design are parts of quality assurance should also focus on bug prevention.For software, quality and productivity are indistinguishable because the cost of a software copy is trivial.The biggest part of software cost is the cost of bugs: the cost of detecting them, the cost of correcting them, the cost of designing tests that discover them, and the cost of running those tests.Where as the manufacturing cost of a software is trivial. Testing and Quality assurance costs for 'manufactured' items can be as low as 2% in consumer products or as high as 80% in products such as space-ships, nuclear reactors, and aircrafts, where failures threaten life.If inspection is good and all errors are caught as they occur, inspection costs will dominate, and again the net cost will suffer. There is a trade off between quality assurance costs and manufacturing costs: If sufficient time is not spent in quality assurance, the reject rate will be high and so will be the net cost.Productivity is measured by the sum of the costs of the material, the rework, and the discarded componenets, and the cost of quality assurance and testing.

If flaws are discovered at any stage, the product is either discarded or cycled back for rework and correction.In production of comsumer goods and other products, every manufacturing stage is subjected to quality control and testing from component to final stage.History says that even well written programs still have 1-3 bugs per hundred statements.MYTH: Good programmers write code without bugs.Testing consumes atleast half of the time and work required to produce a functional program.