TEAM II - NEED FOR SOFTWARE TESTING

Testing is usually performed for the following purposes:

• To improve quality.
  Quality means the conformance to the specified design requirement. Being correct, the minimum requirement of quality, means performing as required under specified circumstances. Debugging, a narrow view of software testing, is performed heavily to find out design defects by the programmer. The imperfection of human nature makes it almost impossible to make a moderately complex program correct the first time. Finding the problems and get them fixed is the purpose of debugging in programming phase.
• For Verification & Validation (V&V)
  Another important purpose of testing is verification and validation (V&V). Testing can serve as metrics. It is heavily used as a tool in the V&V process. Testers can make claims based on interpretations of the testing results, which either the product works under certain situations, or it does not work. We can also compare the quality among different products under the same specification, based on results from the same test.
  We can not test quality directly, but we can test related factors to make quality visible. Quality has three sets of factors -- functionality, engineering, and adaptability. These three sets of factors can be thought of as dimensions in the software quality space. Each dimension may be broken down into its component factors and considerations at successively lower levels of detail.
• Some of the most frequently cited quality considerations.
  Functionality (exterior quality)
  Engineering (interior quality)
  Adaptability (future quality)
  Correctness
  Efficiency
  Flexibility
  Reliability
  Testability
  Reusability
  Usability
  Documentation
  Maintainability
  Integrity
  Structure
  Good testing provides measures for all relevant factors. The importance of any particular factor varies from application to application.
• For reliability estimation
  Software reliability has important relations with many aspects of software, including the structure, and the amount of testing it has been subjected to. Based on an operational profile (an estimate of the relative frequency of use of various inputs to the program ), testing can serve as a statistical sampling method to gain failure data for reliability estimation.
  Software testing is not mature. It still remains an art, because we still cannot make it a science. We are still using the same testing techniques invented 20-30 years ago, some of which are crafted methods or heuristics rather than good engineering methods. Software testing can be costly, but not testing software is even more expensive, especially in places that human lives are at stake. Solving the software-testing problem is no easier than solving the Turing halting problem. We can never be sure that a piece of software is correct. We can never be sure that the specifications are correct. No verification system can verify every correct program. We can never be certain that a verification system is correct either.