Assessing, Comparing, and Combining Statechart- based testing and Structural testing: An Experiment

Although models have been proven to be helpful in a number of software engineering activities there is still significant resistance to model-driven development. This paper investigates one specific aspect of this larger problem. It addresses the impact of using statecharts for testing class clusters that exhibit a state-dependent behavior. More precisely, it reports on a controlled experiment that investigates their impact on testing fault-detection effectiveness. Code-based, structural testing is compared to statechart-based testing and their combination is investigated to determine whether they are complementary. Results show that there is no significant difference between the fault detection effectiveness of the two test strategies but that they are significantly more effective when combined. This implies that a cost-effective strategy would specify statechart-based test cases early on, execute them once the source code is available, and then complete them with test cases based on code coverage analysis

Can we avoid high coupling?

It is considered good software design practice to organize source code into modules and to favour within-module connections (cohesion) over between-module connections (coupling), leading to the oft-repeated maxim "low coupling/high cohesion". Prior research into network theory and its application to software systems has found evidence that many important properties in real software systems exhibit approximately scale-free structure, including coupling; researchers have claimed that such scale-free structures are ubiquitous. This implies that high coupling must be unavoidable, statistically speaking, apparently contradicting standard ideas about software structure. We present a model that leads to the simple predictions that approximately scale-free structures ought to arise both for between-module connectivity and overall connectivity, and not as the result of poor design or optimization shortcuts. These predictions are borne out by our large-scale empirical study. Hence we conclude that high coupling is not avoidable--and that this is in fact quite reasonable

A replicated assessment and comparison of common software cost modeling techniques

Delivering a software product on time, within budget, and to an agreed level of quality is a critical concern for many software organizations. Underestimating software costs can have detrimental effects on the quality of the delivered software and thus on a company's business reputation and competitiveness. On the other hand, overestimation of software cost can result in missed opportunities to funds in other projects. In response to industry demand, a myriad of estimation techniques has been proposed during the last three decades. In order to assess the suitability of a technique from a diverse selection, its performance and relative merits must be compared. The current study replicates a comprehensive comparison of common estimation techniques within different organizational contexts, using data from the European Space Agency. Our study is motivated by the challenge to assess the feasibility of using multi-organization data to build cost models and the benefits gained from company-specific data collection. Using the European Space Agency data set, we investigated a yet unexplored application domain, including military and space projects. The results showed that traditional techniques, namely, ordinary least-squares regression and analysis of variance outperformed Analogy-based estimation and regression trees. Consistent with the results of the replicated study no significant difference was found in accuracy between estimates derived from company-specific data and estimates derived from multi-organizational data

A comprehensive and systematic methodology for client-server class integration testing

This article is a first attempt towards a comprehensive, systematic methodology for class interface testing in the context of client/server relationships. The proposed approach builds on and combines existing techniques. It first consists in selecting a subset of the method sequences defined for the class testing of the client class, based on an analysis of the interactions between the client and the server methods. Coupling information is then used to determine the conditions, i.e., values for parameters and data members, under which the selected client method sequences are to be executed so as to exercise the interaction. The approach is illustrated by means of an abstract example and its cost-effectiveness is evaluated through a case study