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Scenarios (Use cases) – being descriptions of sequences of interactions between two or more partners, usually between a system and its users – have attracted much attention and gained wide-spread use in requirements and software engineering over the last couple of years. In scenarios, the functionality and behavior of a (software) system is captured in a user-centered perspective. To date, scenarios are mainly used in the requirements elicitation and analysis phase of software development. Even though scenarios are mainly used in system analysis, the use of scenarios in other phases of software development is of much interest, as it could help to cut cost by reuse and improved validation and verification. As scenarios form a kind of abstract test cases for the system under development, the idea to use them to derive test cases for system test is quite intriguing. Yet in practice, scenarios from the analysis phase are seldom used to create concrete system test cases. An analysis of the central problems of software testing, and of the reasons why scenarios from the analysis phase are not used for creating test cases for system test, leads us to proposing the following premises or concepts which we consider to be valuable approaches to improve testing, and that consequently serve as a basis for the approach presented in this thesis: * Reuse of analysis scenarios for validation purposes and in testing. * Integration of test methods & activities and of the methods & activities of the software development methodology used. * Creation of test cases for system test in a systematic manner and early in the development cycle. * Modeling the dependencies and relationships among scenarios and using this dependency model to refine test case derivation from the scenario model. In this document, a method is developed and described that is based on the concepts presented above and on the deficiencies found in existing approaches. A definite step-procedure for creating scenarios is defined and further use of analysis scenarios in development and testing is discussed. We call the approach the SCENT-Method: A method for SCENario-based validation and Test of software. The main issues of requirements elicitation and documentation are analyzed, and the advantages and disadvantages of formal specification languages versus natural language are discussed. A detailed step-by-step procedure for the creation of descriptive, narrative scenarios is defined and a template to help describe, structure and document natural language scenarios is presented. Natural language scenario descriptions are formalized in statecharts. This helps to avoid or at least alleviate some of the problems of natural language specifications (ambiguity, inconsistencies, imprecise or vague expressions, and the like). These statecharts – being a more formal representation of the narrative scenarios – are used to systematically derive test cases from. Furthermore, the statecharts-based functional model is annotated with non-functional requirements and data, and used to validate the system. Dependencies and relations among scenarios are captured and modeled in a special model that stands complementary to the behavioral model. This so-called SCENT dependency chart is used to derive further test cases, and thus to expand and refine the test suite created from the behavioral model. A language and a notation are defined to capture and document the dependencies among the scenarios. In an example we illustrate how to use this language and notation. The tester uses the formalized and annotated scenarios and the dependency charts for deriving test cases for system test. This is done in a systematic way by traversing paths in the statecharts and the dependency charts, respectively. First results, that have been gained by applying the method to real projects in an international company, are presented and discussed, and problems and open questions are addressed.

Szenarienbasiertes Validieren und Testen von Softwaresystem...

Szenarienbasiertes Validieren und Testen von Softwaresystemen [Scenario-based validation and test of software systems (in German)]

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