10.7 Summary

Testing plays a critical role in quality assurance for software. Due to the limitations of the verification methods for the previous phases, design and requirement faults also appear in the code. Testing is used to detect these errors, in addition to the errors introduced during the coding phase.

Testing is a dynamic method for verification and validation, where the system to be tested is executed and the behavior of the system is observed. Due to this, testing observes the failures of the system, from which the presence of faults can be deduced. However, separate activities have to be performed to identify the faults (and then remove them).

There are two approaches to testing: black-box and white-box. In black-box testing, the internal logic of the system under testing is not considered and the test cases are decided from the specifications or the requirements. It is often called functional testing. Equivalence class partitioning, boundary value analysis, and cause-effect graphing are examples of methods for selecting test cases for black-box testing. State-based testing is another approach in which the system is modeled as a state machine and then this model is used to select test cases using some transition or path based coverage criteria. State-based testing can also be viewed as grey-box testing in that it often requires more information than just the requirements.

In white-box testing, the test cases are decided entirely on the internal logic of the program or module being tested. The external specifications are not considered. Often...