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Search Results: 1 - 10 of 27466 matches for " Robert Feldt "
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Do System Test Cases Grow Old?
Robert Feldt
Computer Science , 2013,
Abstract: Companies increasingly use either manual or automated system testing to ensure the quality of their software products. As a system evolves and is extended with new features the test suite also typically grows as new test cases are added. To ensure software quality throughout this process the test suite is continously executed, often on a daily basis. It seems likely that newly added tests would be more likely to fail than older tests but this has not been investigated in any detail on large-scale, industrial software systems. Also it is not clear which methods should be used to conduct such an analysis. This paper proposes three main concepts that can be used to investigate aging effects in the use and failure behavior of system test cases: test case activation curves, test case hazard curves, and test case half-life. To evaluate these concepts and the type of analysis they enable we apply them on an industrial software system containing more than one million lines of code. The data sets comes from a total of 1,620 system test cases executed a total of more than half a million times over a time period of two and a half years. For the investigated system we find that system test cases stay active as they age but really do grow old; they go through an infant mortality phase with higher failure rates which then decline over time. The test case half-life is between 5 to 12 months for the two studied data sets.
A Factorial Experiment on Scalability of Search Based Software Testing
Arash Mehrmand,Robert Feldt
Computer Science , 2011,
Abstract: Software testing is an expensive process, which is vital in the industry. Construction of the test-data in software testing requires the major cost and to decide which method to use in order to generate the test data is important. This paper discusses the efficiency of search-based algorithms (preferably genetic algorithm) versus random testing, in soft- ware test-data generation. This study di?ers from all previous studies due to sample programs (SUTs) which are used. Since we want to in- crease the complexity of SUTs gradually, and the program generation is automatic as well, Grammatical Evolution is used to guide the program generation. SUTs are generated according to the grammar we provide, with di?erent levels of complexity. SUTs will first undergo genetic al- gorithm and then random testing. Based on the test results, this paper recommends one method to use for automation of software testing.
Tester Interactivity makes a Difference in Search-Based Software Testing: A Controlled Experiment
Bogdan Marculescu,Simon Poulding,Robert Feldt,Kai Petersen,Richard Torkar
Computer Science , 2015,
Abstract: Context: Search-based software testing promises to provide users with the ability to generate high-quality test cases, and hence increase product quality, with a minimal increase in the time and effort required. One result that emerged out of a previous study to investigate the application of search-based software testing (SBST) in an industrial setting was the development of the Interactive Search-Based Software Testing (ISBST) system. ISBST allows users to interact with the underlying SBST system, guiding the search and assessing the results. An industrial evaluation indicated that the ISBST system could find test cases that are not created by testers employing manual techniques. The validity of the evaluation was threatened, however, by the low number of participants. Objective: This paper presents a follow-up study, to provide a more rigorous evaluation of the ISBST system. Method: To assess the ISBST system a two-way crossover controlled experiment was conducted with 58 students taking a Verification and Validation course. The NASA Task Load Index (NASA-TLX) is used to assess the workload experienced by the participants in the experiment. Results: The experimental results validated the hypothesis that the ISBST system generates test cases that are not found by the same participants employing manual testing techniques. A follow-up laboratory experiment also investigates the importance of interaction in obtaining the results. In addition to this main result, the subjective workload was assessed for each participant by means of the NASA-TLX tool. The evaluation showed that, while the ISBST system required more effort from the participants, they achieved the same performance. Conclusions: The paper provides evidence that the ISBST system develops test cases that are not found by manual techniques, and that interaction plays an important role in achieving that result.
Models for Integrating UX into Software Engineering Practice: an Industrial Validation
Pariya Kashfi,Robert Feldt,Agneta Nilsson,Richard Berntsson Svensson
Computer Science , 2014,
Abstract: The user's overall experience and perception of functionalities and qualities of a product, User eXperience (UX), is becoming increasingly important for success of software products. Yet, many software companies face challenges with their UX practices, hence fail to achieve a good UX in their products. Part of these challenges are rooted in inadequate knowledge and awareness about UX but also in that UX models are commonly not well integrated with existing software engineering (SE) models and concepts. Therefore, we present two SE-specific models of UX for practitioners: (i) a layered model that shows the relation between functional, quality, and UX requirements, and (ii) a general, UX-aware software process overview model that shows the additional concepts and activities that can help achieve a good UX. Validation of the models in interviews with 12 practitioners and researchers generally found the models useful for practice; for instance to raise knowledge and awareness about UX, improve communications regarding UX and facilitating making UX-aware decisions in the development process. In total, we identified six different areas of use for the models.
Test Set Diameter: Quantifying the Diversity of Sets of Test Cases
Robert Feldt,Simon Poulding,David Clark,Shin Yoo
Computer Science , 2015,
Abstract: A common and natural intuition among software testers is that test cases need to differ if a software system is to be tested properly and its quality ensured. Consequently, much research has gone into formulating distance measures for how test cases, their inputs and/or their outputs differ. However, common to these proposals is that they are data type specific and/or calculate the diversity only between pairs of test inputs, traces or outputs. We propose a new metric to measure the diversity of sets of tests: the test set diameter (TSDm). It extends our earlier, pairwise test diversity metrics based on recent advances in information theory regarding the calculation of the normalized compression distance (NCD) for multisets. An advantage is that TSDm can be applied regardless of data type and on any test-related information, not only the test inputs. A downside is the increased computational time compared to competing approaches. Our experiments on four different systems show that the test set diameter can help select test sets with higher structural and fault coverage than random selection even when only applied to test inputs. This can enable early test design and selection, prior to even having a software system to test, and complement other types of test automation and analysis. We argue that this quantification of test set diversity creates a number of opportunities to better understand software quality and provides practical ways to increase it.
Fabry Disease and Early Stroke
U. Feldt-Rasmussen
Stroke Research and Treatment , 2011, DOI: 10.4061/2011/615218
Abstract: Fabry disease, an X-linked lysosomal storage disorder, results from deficient activity of the enzyme α-galactosidase A. Affected males with the classic phoenotype have acroparaesthesias, hypohidrosis, and corneal opacities in childhood and develop renal failure, cardiac hypertrophy or strokes in the third to fifth decade of life. Some female heterozygotes are asymptomatic, some as severely affected as males. The natural history of Fabry patients includes transitory cerebral ischaemia and strokes, even in very young persons of both genders. The mechanism is partly due to vascular endothelial accumulation of GL-3. White matter lesions on MRI occur. Both males and females can be safely treated with enzyme replacement; and thus screening for Fabry disease of young stroke populations should be considered. There are, however, no hard data of treatment effect on mortality and morbidity. The analyses of results from ongoing studirs will add to the decision on whether or not to screen young stroke patients for Fabry disease. Finally, stroke prophylactic therapy should be used liberally in patients of both genders with verified Fabry disease. This includes primary prevention such as lifestyle counseling, targeting blood pressure, managing atrial fibrillation, diabetes mellitus, hyperlipidaemia, and ASA. 1. Introduction Fabry disease is a rare X-linked inborn error of glycosphingolipid metabolism resulting from reduced production of lysosomal (α-galactosidase A (α-Gal A)) [1]. The enzymatic deficiency leads to lysosomal accumulation of glycosphingolipids, primarily globotriaosylceramide (GL-3), particularly in vascular endothelial cells throughout the body. Affected males and symptomatic heterozygous females with the classical phenotype have manifestations in childhood or adolescence including angiokeratoma, acroparesthesia, gastrointestinal manifestations, and corneal opacities. With advancing age, the progressive vascular involvement results in renal insufficiency, cardiac disease, and strokes [1]. Patients with Fabry disease have a shortened life expectancy due to the development of a specific vasculopathy. Male patients typically develop renal impairment in their third or fourth decade of life, as well as cardiac hypertrophy and conduction abnormalities. Life expectancy is reduced with a median life expectancy between 50 and 57 years for the male population [2–4]. In females, the disease is more variable, with less involvement of the kidneys, but life span is shortened as well [2, 3, 5]. In female patients, cardiac disease and cerebral white matter lesions
High-density lipoprotein: does it have a dark side?
Joan M Von Feldt
Arthritis Research & Therapy , 2008, DOI: 10.1186/ar2527
Abstract: In the previous issue of Arthritis Research & Therapy, Hahn and colleagues [1] provided a comprehensive review of altered lipoprotein metabolism in chronic inflammatory states, and proposed that this altered metabolism may be important in the pathogenesis of accelerated atherosclerosis in rheumatic disease. Cardiovascular morbidity and mortality have been associated with chronic rheumatic diseases, most notably systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Although co-morbidities may frequently co-exist in patients with RA and SLE as a complication of disease or treatment, both SLE and RA have been identified as independent risk factors for atherosclerotic cardiovascular disease [2,3]. What factors or group of factors increase that risk is under intense investigation. Lipids and lipoproteins have been extensively studied, but have not been shown to be a primary risk factor in SLE and RA. In cohorts of SLE patients studied, cholesterol has not been an independent predictor of atherosclerotic cardiovascular disease [4,5]. Additionally, although there has been a consistent pattern of lower high-density lipoprotein (HDL) cholesterol levels seen in RA patients compared with age- and sex-matched controls, the picture is more mixed with regard to total cholesterol and low-density lipoprotein (LDL) cholesterol levels [6,7]. Therefore, if cholesterol metabolism and transport contribute to the presence and progression of atherosclerosis in these inflammatory states, it is reasonable to consider altered lipoprotein states. In their review, Hahn and colleagues present the accumulated data on pro-inflammatory HDL as a novel biomarker for increased risk of atherosclerosis in patients with SLE and RA.HDL-cholesterol is considered among the best predictors of cardiovascular disease in large populations. However, in the original Framingham study approximately 44% of the events in men and 43% in women occurred in persons with normal HDL-cholesterol levels [8]. Res
High-resolution studies of massive star-forming regions
Thomas Henning,Markus Feldt,Bringfried Stecklum
Physics , 2001,
Abstract: We summarize the status of our program of near-infrared adaptive optics observations of ultracompact HII regions. By means of selected results we demonstrate the usefulness of this technique for disentangling the complexity of massive star-forming regions. The primary scientific aims of our study are the identification of the ionizing stars, the characterization of the stellar population, the clarification of the role of dust for the excitation of the HII region and, last but not least, the search for circumstellar disks surrounding high-mass stars. We present results obtained by adaptive optics observations and additional measurements for G45.45+0.06, G5.89-0.39, and G309.92+0.48 to illustrate our scientific objectives.
Constantes de Movimento para um Potencial Dependente da Velocidade
Castro, A. S. de;Marchesetti, E. L.;Feldt, A.;
Revista Brasileira de Ensino de Física , 2002, DOI: 10.1590/S1806-11172002000300004
Abstract: geometric continuous symmetries for a closed system of particles are investigated. it is supposed that the interactions are derivable from a velocity-dependent potential. both the constraints on the form of the potential and the conservation principles resulting from the continuous space- time symmetries are derived. darwin's lagrangian is used as an illustration for the case of electric charges in slow motion in maxwell-lorentz's formulation of classical electrodynamics and the gauge-dependent linear momentum, angular momentum and energy are obtained.
Constantes de Movimento para um Potencial Dependente da Velocidade
Castro A. S. de,Marchesetti E. L.,Feldt A.
Revista Brasileira de Ensino de Física , 2002,
Abstract: Simetrias geométricas contínuas para um sistema fechado de partículas s o investigadas. Por suposto, as intera es s o deriváveis de uma fun o potencial dependente das velocidades das partículas. Tanto os vínculos sobre a forma da fun o potencial quanto os princípios de conserva o resultantes das simetrias espa o-temporais contínuas s o derivados. A lagrangiana de Darwin é utilizada como ilustra o para o caso do movimento lento de cargas elétricas na formula o deMaxwell-Lorentz da eletrodinamica clássica. O momento linear, o momento angular e a energia, quantidades dependentes de calibre, s o obtidos.
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