Software Architecture Improvement through Test-Driven Development

This research involves empirical software engineering studies applied in academic and professional settings to assess the influence of test-driven development on software quality. Particular focus is given to internal software design quality. Pedagogical implications are also examined. Initial results and the study protocol and plans will be presented

From RS-232 to Object Request Brokers: Incremental Object-Oriented Networking Projects

Selecting an appropriate set of laboratory experiences and projects for a Data Communications and Computer Networks course can be difficult due to the broad and deep nature of the topics. Emphasis may be placed on many networking aspects including design, evaluation, efficiency, security, protocols, tools, and applications. This paper presents a set of projects that attempt to integrate software engineering and systems administration topics. The projects emphasize network application programming. Particular attention will be given to a sequence of incremental projects using an object-oriented approach including the use of the Unified Modeling Language (UML) and a design pattern

Insights from Population Genomics to Enhance and Sustain Biological Control of Insect Pests

Biological control—the use of organisms (e.g., nematodes, arthropods, bacteria, fungi, viruses) for the suppression of insect pest species—is a well-established, ecologically sound and economically profitable tactic for crop protection. This approach has served as a sustainable solution for many insect pest problems for over a century in North America. However, all pest management tactics have associated risks. Specifically, the ecological non-target effects of biological control have been examined in numerous systems. In contrast, the need to understand the short- and long-term evolutionary consequences of human-mediated manipulation of biological control organisms for importation, augmentation and conservation biological control has only recently been acknowledged. Particularly, population genomics presents exceptional opportunities to study adaptive evolution and invasiveness of pests and biological control organisms. Population genomics also provides insights into (1) long-term biological consequences of releases, (2) the ecological success and sustainability of this pest management tactic and (3) non-target effects on native species, populations and ecosystems. Recent advances in genomic sequencing technology and model-based statistical methods to analyze population-scale genomic data provide a much needed impetus for biological control programs to benefit by incorporating a consideration of evolutionary consequences. Here, we review current technology and methods in population genomics and their applications to biological control and include basic guidelines for biological control researchers for implementing genomic technology and statistical modeling

Do covariances between maternal behavior and embryonic physiology drive sex-ratio evolution under environmental sex determination?

Fisherian sex-ratio theory predicts sexual species should have a balanced primary sex ratio. However, organisms with environmental sex determination (ESD) are particularly vulnerable to experiencing skewed sex ratios when environmental conditions vary. Theoretical work has modeled sex-ratio dynamics for animals with ESD with regard to two traits predicted to be responsive to sex-ratio selection: (1) maternal oviposition behavior and (2) sensitivity of embryonic sex determination to environmental conditions, and much research has since focused on how these traits influence offspring sex ratios. However, relatively few studies have provided estimates of univariate quantitative genetic parameters for these two traits, and the existence of phenotypic or genetic covariances among these traits has not been assessed. Here, we leverage studies on three species of reptiles (two turtle species and a lizard) with temperature-dependent sex determination (TSD) to assess phenotypic covariances between measures of maternal oviposition behavior and thermal sensitivity of the sex-determining pathway. These studies quantified maternal behaviors that relate to nest temperature and sex ratio of offspring incubated under controlled conditions. A positive covariance between these traits would enhance the efficiency of sex-ratio selection when primary sex ratio is unbalanced. However, we detected no such covariance between measures of these categories of traits in the three study species. These results suggest that maternal oviposition behavior and thermal sensitivity of sex determination in embryos might evolve independently. Such information is critical to understand how animals with TSD will respond to rapidly changing environments that induce sex-ratio selection

Empirical Software Engineering in Industry Short Courses

This paper reports on a pilot project that incorporated small empirical studies in three industry short courses. These laboratory experiments were one component of a larger leveled study on the effects of test-driven development (TDD) on internal software quality. The approach is proposed to have pedagogical value to student-developers by improving their understanding and appreciation for empirical evidence, to instructors by providing feedback through surveys and exercises, and to the community at large by reporting results of the studies. Pre-experiment surveys in the three pilot experiments revealed large differences in programmer opinions of TDD. Possible correlations to development environment and programmer experience will be proposed. Post-experiment surveys revealed improvements in programmer opinions of TDD following the experiment exercises. Crafting sufficiently small but interesting assignments proved to be challenging. Few complete solutions were submitted and some developers were unwilling to submit their partial solutions. Positive observations will be made regarding the use of experiments in short courses. For instance, participating in the study encourages analytical thinking, prompts developers to evaluate alternative approaches, and instills the value of empirical evidence. Ethical concerns regarding threats to validity are raised and addressed. The authors find that ethical considerations not only support performing such studies, but encourage it as the duty of software professionals

A Leveled Examination of Test-Driven Development Acceptance

Test-driven development (TDD) has garnered considerable attention in professional settings and has made some inroads into software engineering and computer science education. A series of leveled experiments were conducted with students in beginning undergraduate programming courses through upper-level undergraduate, graduate, and professional training courses. This paper reports that mature programmers who try TDD are more likely to choose TDD over a similar test-last approach. Additionally this research reveals differences in programmer acceptance of TDD between beginning programmers who were reluctant to adopt TDD and more mature programmers who were more willing to adopt TDD. Attention is given to confounding factors, and future studies aimed at resolving these factors are identified. Finally proposals are made to improve early programmer acceptance of TDD

On the Influence of Test-Driven Development on Software Design

Test-driven development (TDD) is an agile software development strategy that addresses both design and testing. This paper describes a controlled experiment that examines the effects of TDD on internal software design quality. The experiment was conducted with undergraduate students in a software engineering course. Students in three groups completed semester-long programming projects using either an iterative Test-First (TDD), iterative Test-Last, or linear Test-Last approach. Results from this study indicate that TDD can be an effective software design approach improving both code-centric aspects such as object decomposition, test coverage, and external quality, and developer-centric aspects including productivity and confidence. In addition, iterative development approaches that include automated testing demonstrated benefits over a more traditional linear approach with manual tests. This study demonstrates the viability of teaching TDD with minimal effort in the context of a relatively traditional development approach. Potential dangers with TDD are identified regarding programmer motivation and discipline. Pedagogical implications and instructional techniques which may foster TDD adoption will also be referenced

Food plants and life histories of sawflies of the families Argidae and Tenthredinidae (Hymenoptera) in Costa Rica, a supplement

Food plants and information on life history are presented for six species of Argidae and four species of Tenthredinidae in Costa Rica. The Argidae include cocoons of Atomacera josefernandezi Smith, sp. n., found on Hampea appendiculata (Donn. Sm.) Standl. (Malvaceae) and likely feeding on its leaves before pupation, and larvae of Eriglenum tristum Smith feeding on Machaerium seemanii Benth. Ex Seem. (Fabaceae), Ptenos leucopodus (Cameron) feeding on Inga oerstediana Benth. and I. vera Willd. (Fabaceae), Ptilia peleterii (Gray) feeding on Cnestidium rufescens (Connaraceae), and Scobina lepida (Klug) and S. notaticollis (Konow) feeding on Sida rhombifolia L. (Malvaceae). The Tenthredinidae include larvae of Dochmioglene crassa (Cameron) feeding on the fern Lomariopsis vestita E. Fourn. (Lomariopsidaceeae), Dochmiogleme Smith03 feeding on Blechnum occidentale L. (Blechnaceae), Waldheimia laeta (Cameron) feeding on Cissus alata Jacq. (Vitaceae), and Waldheimia lucianocapellii Smith, sp. n., feeding on Davilla nitida (Vahl) Kubitzki (Dilleniaceae). Waldheimia lucianocapellii is described from specimens from both Panama and Costa Rica. Selandria crassa Cameron, 1883 is a comb. n. in Dochmioglene