objectives or goals for software testing - csmates.com

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Objectives for software testing

Software testing is usually performed for the following major reasons.
  • Software Quality Improvement
  • Verification and Validation
  • Software Reliability Estimation

1. Software Quality Improvement

As computers and software are used in critical applications, the outcome of a bug can be served. Bugs can cause huge losses. Bugs in critical systems have:
  • Caused Airplane Crashes
  • Allowed space shuttle missions to go awry.
  • Halted trading on the stock market, and 
  • Worse
Bugs can kill and cause disasters. The so-called year 2000 (Y2K) bug could have resulted in a more screeching halt on the first day of the century. In a computerized embedded world, the quality and reliability of software is matter of life and death.

Software quality means conformance to the specified software design requirements. 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 humans 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 the programming phase.

2. Verification and Validation

Another important objective of software 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 doesn't work.

Software quality can't be tested directly but the related factors to make quality visible can be tested. Quality has three sets of factors:
  • Functionality
  • Engineering
  • 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 details. 
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Good testing provides measures for all relevant factors. The importance of any particular factor varies from application to application. Any system where human lives are at stake must place extreme emphasis on reliability and integrity. 

In the typical business system, usability and maintainability are the key factors, while for a one-time scientific program neither may be significant. Our testing, to be fully effective, must be geared to measuring each relevant factor and thus forcing quality to become tangible and visible.

Tests with the purpose of validating the product works are named clean tests or positive tests. The drawbacks are that it can only validate that the software works for the specified test cases. A finite number of tests can't validate that the software works for all situations. On the contrary, only one failed test is sufficient enough to show that the software doesn't work.

Diry tests or negative tests refer to the tests aiming at breaking the software, or showing that it doesn't work. A piece of software must have sufficient exception handling capabilities to survive a significant level of dirty tests.

A testable design is a design that can be easily validated, falsified, and maintained. Because testing is a rigorous effort and requires significant time and cost,  design for testability is also an important design rule for software development.

3. Software Reliability Estimation

Software reliability has important relations with many aspects of the software, including the structure, and the amount of testing it has been subjected to.

The objective of testing is to discover the residual design errors before delivery to the customer. The failure data during the testing process are taken down in order to estimate software reliability. The testing process may function with regular feedback from the reliability analysis to the testers and designers.
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Based on an operational profile, testing can serve as a statistical sampling method to gain failure data for software reliability estimation.
 

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