Software Testing Methodology

Software Testing methodology Unit -1 Introduction:purpose of testing ,dichotomies,model for testing,consequence of bugs

The purpose of testing • The purpose of testing is to show that program has bugs. the bug is manifested in deviations from an expected behaviour • The purpose of testing is to show that software works. • The purpose of testing is to show that software doesn’t works. • The purpose of testing is to reduce the risk of the software. • The purpose of testing is to know the productivity and quality of the software

Continued… 1)Test and test design as a part of quality assurance should also focus on bug prevention. 2)To the extent testing and testing design donot prevent the bugs , they should be able to identify the symptoms caused by the bugs and finally tests should provide a clear diagnosis so that the bug can be easily corrected. 3)Now bug prevention is the testings first goal. ->a prevented bug is better than detected or corrected bug . If the bug is

Productivity and quality in software • 1)once in a production of software every manufacturing phase is subjected to quality control and testing from component source inspection to final testing before shipping . If flaws are discovered at any stage , the widget or the part of it will be discarded or cycled back for rework and correction. • 2)Productivity is measured by the sum of costs of the material,the rework,and the discarded components and the cost of quality assurance and testing. • 3)there is a trade off between quality assurance costs and manufacturing costs . • ->insufficient effort is spent in quality

• ->conversely ,if inspection is do good that all faults are caught as they occur , inspection cost will dominate ,and again net costs will suffer. 4)The manufacturing process designers attempts to establish a level of testing and a quality assurance , that minimizes a net cost for the given quality objective. 5)Productivity and quality assurance for a manufactured items can be low as 2% for a consumer products or high as 80% in the products such as spaceships , nuclear

Goals of the testing • 1)As we discussed in the 3rd slide that bug prevention is the primary goal rather than detecting or correcting. • 2)unfortunately we cant achieve this ideal ,despite our efforts there will be bugs as we are human. • 3)to the extent that testing fails to reach its primary goal, bug prevention ,it must go to the secondary goal bug discovery. • 4)bugs are not always obvious. • 5)the test design must document expectations , test procedure in details and

Phases in testers mental life • While testing any software product There is an attitudinal progression in tester , characterized by the following 5 phases. • Phase 0:There is no difference in testing and debugging , other than in support of debugging testing has no purpose. • Phase 1:the purpose of testing is to show that software works . • Phase 2:the purpose of testing is to show that software does not works.

• Phase 3:the purpose of testing is not to prove anything , but to reduce the perceived risk of not working to an acceptable value. • Phase 4:testing is not an act , it’s a mental discipline that results in low risks software without taking much testing effort.