David A. Carrington

A framework for specification-based testing

Test templates and a test template framework are introduced as useful concepts in specification-based testing. The framework can be defined using any model-based specification notation and used to derive tests from model-based specifications-in this paper, it is demonstrated using the Z notation. The framework formally defines test data sets and their relation to the operations in a specification and to other test data sets, providing structure to the testing process. Flexibility is preserved, so that many testing strategies can be used. Important application areas of the framework are discussed, including refinement of test data, regression testing, and test oracles.

Empirical Evaluation of Aesthetics-based Graph Layout

Many automatic graph layout algorithms have been designed and implemented to display relational data in a graphical (usually node-arc) manner. The success of these algorithms is typically measured by their computational efficiency and the extent to which they conform to aesthetic criteria (for example, minimising the number of crossings, maximising symmetry). Little research has been performed on the usability aspects of such algorithms: do they produce graph drawings that make the embodied information easy to use and understand? Is the computational effort expended on conforming to the assumed aesthetic criteria justifiable with respect to better usability? This paper reports on usability studies that were performed to investigate the merit of automatic graph layout algorithms with respect to human use. The paper describes three ways in which this issue has been considered experimentally: first, investigating individual aesthetic criteria in simple, abstract graph structures; second, investigating the results of common automatic graph layout algorithms; and third, investigating individual aesthetic criteria and other relevant secondary notations in Unified Modeling Language class and collaboration diagrams. The results show that the use of only some aesthetics affect usability significantly, and that the semantic domain of the graph drawings affects which aesthetic criteria need to be emphasised.

A Formal Mapping between UML Models and Object-Z Specifications

This paper presents a precise and descriptive semantics for core modeling concepts in Object-Z and a formal description for UML class constructs. Given the formal descriptions, it also provides a formal semantic mapping between the two languages at the meta-level, which makes our translation more systematic. Any verification of UML models can take place on their corresponding Object-Z specifications using reasoning techniques provided for Object-Z. With this approach, we provide not only a precise semantic basis for UML but also a sound mechanism for reasoning about UML models.

Formalizing the UML class diagram using object-Z

To produce a precise and analyzable software model, it is essential for the modeling technique to have formality in the syntax and the semantics of its notation, and to allow rigorous analysis of its models. In this sense, UML is not yet a truly precise modeling technique. This paper presents a formal basis for the syntactic structures and semantics of core UML class constructs, and also provides a basis for reasoning about UML class diagrams. The syntactic structures of UML class constructs and the rules for developing a well-formed class diagram are precisely described using the Z notation. Based on this formal description, UML class constructs are then translated to Object-Z constructs. Proof techniques provided for Object-Z can be used for reasoning about these class diagrams.

UML class diagram syntax: an empirical study of comprehension

Despite UML being considered a software engineering standard, the UML syntactic notations used in texts, papers, documentation and CASE tools are often different. The decision as to which of the semantically equivalent notational variations to use appears to be according to the personal preference of the author or publisher, rather than based on any consideration of the ease with which the notation can be understood by human readers. This paper reports on an experiment that takes a human comprehension perspective on UML class diagram notational variants. Five notations were considered: for each, two semantically equivalent, yet syntactically different, variations were chosen from published texts. Our experiment required subjects to indicate whether a supplied specification matched each of a set of experimental diagrams. The results reveal that the best performing notation may depend on the task for which it is used, and that our personal, intuitive predictions intuitions (which were based in the complexity of the notation) were partly confirmed.

Graph layout aesthetics in UML diagrams: User preferences

The merit of automatic graph layout algorithms is typically judged by their computational eciency and the extent to which they conform to aesthetic criteria (for example, minimising the number of crossings, maximising orthogonality). Experiments investigating the worth of such algorithms from the point of view of human usability can take dierent forms, depending on whether the graph has meaning in the real world, the nature of the usability measurement, and the eect being investigated (algorithms or aesthetics). Previous studies have investigated performance on abstract graphs with respect to both aesthetics and algorithms, nding support for reducing the number of crossings and bends, and increasing the display of symmetry. This paper reports on preference experiments assessing the eect of individual aesthetics in the application domain of UML diagrams. Subjects’ preferences for one diagram over another were collected as quantitative data. Their stated reasons for their choice were collected as qualitative data. Analysis of this data enabled us to produce a priority listing of aesthetics for this domain. These UML preference results reveal a difference in aesthetic priority from those of previous domain-independent experiments.

A tale of two paradigms: Formal methods and software testing

There are two camps of software developers: formal methods advocates battling against traditionalist supporters of software testing and assessment metrics. Surely, as Turing observed, we will (must) never do away with testing in some form. But clearly, formal methods cannot be ignored, and must be the basis of quality assurance in some form. Important impacts of specifications on testing are in test selection, test oracles, and analysis of test suites and theoretical results of testing. We examine uses of formal specifications in software testing, particularly, roles of Z specifications in software testing. We also present our unifying framework for specification-based testing, which is founded on Z.

Test templates: a specification-based testing framework

Test templates and a test template framework are introduced as useful concepts in specification-based testing. The framework can be defined using any model-based specification notation and used to derive tests from model-based specifications. It is demonstrated using the Z notation. The framework formally defines test data sets and their relation to the operations in a specification and other test data sets, providing structure to the testing process. Flexibility is also preserved, so that many testing strategies can be used. Important application areas of the framework are discussed, including refinement of test data, regression testing, and test oracles.<<ETX>>

User Preference of Graph Layout Aesthetics: A UML Study

The merit of automatic graph layout algorithms is typically judged on their computational efficiency and the extent to which they conform to aesthetic criteria (for example, minimising the number of crossings, maximising symmetry). Experiments investigating the worth of such algorithms from the point of view of human usability can take a number of different forms, depending on whether the graph has meaning in the real world, the nature of the usability measurement, and the effect being investigated (algorithms or aesthetics). Previous studies have investigated performance on abstract graphs with respect to both aesthetics and algorithms, finding support for reducing the number of crossings and bends, and increasing the display of symmetry. This paper reports on preference experiments assessing the effect of individual aesthetics in the application domain of UML diagrams, resulting in a priority listing of aesthetics for this domain. The results reveal a difference in aesthetic priority from those of previous domain-independent experiments.

From Object-Z specifications to ClassBench test suites

This paper describes a method for specification‐based class testing that incorporates test case generation, execution, and evaluation based on formal specifications. This work builds on previous achievements in the areas of specification‐based testing and class testing by integrating the two within a single framework. The initial step of the method is to generate test templates for individual operations from a specification written in the Object‐Z specification language. These test templates are combined to produce a finite state machine for the class that is used as the basis for test case execution using the ClassBench test execution framework. An oracle derived from the Object‐Z specification is used to evaluate the outputs. The method is explained using a simple example and its application to a more substantial case study is also discussed. Copyright