4.2 Categories of test design techniques (K2)

The purpose of a test design technique is to identify test conditions and test cases.
It is a classic distinction to denote test techniques as black box or white box. Black-box techniques (which include specification-based and experience based techniques) are a way to derive and select test conditions or test cases based on an analysis of the test basis documentation, and the experience of developers, testers and users, whether functional or non-functional, for a component or system without reference to its internal structure. White-box techniques (also called structural or structure-based techniques) are based on an analysis of the structure of the component or system. Both black box and white box are systematic testing techniques which are a part of dynamic testing technique. Dynamic testing involves execution of code.

Some techniques fall clearly into a single category; others have elements of more than one category.

This syllabus refers to specification-based or experience-based approaches as black-box techniques and structure-based as white-box techniques.

Common features of specification-based techniques:
§ Models, either formal or informal, are used for the specification of the problem to be solved, the software or its components.
§ From these models test cases can be derived systematically.

Common features of structure-based techniques:
§ Information about how the software is constructed is used to derive the test cases, for example, code and design.
§ The extent of coverage of the software can be measured for existing test cases, and further test cases can be derived systematically to increase coverage.

Common features of experience-based techniques:
§ The knowledge and experience of people are used to derive the test cases.
.1.1 knowledge of testers, developers, users and other stakeholders about the software, its usage and its environment;
.1.2 Knowledge about likely defects and their distribution.


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