arXiv subjects

Lars Grunske

Publications and source records attributed to Lars Grunske.

27 records · Page 2Linked to original sources

arXiv2021

Towards a Benchmark Set for Program Repair Based on Partial Fixes

Software bugs significantly contribute to software cost and increase the risk of system malfunctioning. In recent years, many automated program-repair approaches have been proposed to automatically fix undesired program behavior. Despite of their great success, specific problems such as fixing bugs with partial fixes still remain unresolved. A partial fix to a known software issue is a programmer's failed attempt to fix the issue the first time. Even though it fails, this fix attempt still conveys important information such as the suspicious software region and the bug type. In this work we do not propose an approach for program repair with partial fixes, but instead answer a preliminary question: Do partial fixes occur often enough, in general, to be relevant for the research area of automated program repair? We crawled 1500 open-source C repositories on GitHub for partial fixes. The result is a benchmark set of 2204 benchmark tasks for automated program repair based on partial fixes. The benchmark set is available open source and open to further contributions and improvement.

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arXiv2020

A Comprehensive Empirical Evaluation of Generating Test Suites for Mobile Applications with Diversity

Context: In search-based software engineering we often use popular heuristics with default configurations, which typically lead to suboptimal results, or we perform experiments to identify configurations on a trial-and-error basis, which may lead to better results for a specific problem. We consider the problem of generating test suites for mobile applications (apps) and rely on \Sapienz, a state-of-the-art approach to this problem that uses a popular heuristic (NSGA-II) with a default configuration. Objective: We want to achieve better results in generating test suites with \Sapienz while avoiding trial-and-error experiments to identify a more suitable configuration of \Sapienz. Method: We conducted a fitness landscape analysis of \Sapienz to analytically understand the search problem, which allowed us to make informed decisions about the heuristic and configuration of \Sapienz when developing \SapienzDiv. We comprehensively evaluated \SapienzDiv in a head-to-head comparison with \Sapienz on 34 apps. Results: Analyzing the fitness landscape of \Sapienz, we observed a lack of diversity of the evolved test suites and a stagnation of the search after 25 generations. \SapienzDiv realizes mechanisms that preserve the diversity of the test suites being evolved. The evaluation showed that \SapienzDiv achieves better or at least similar test results than \Sapienz concerning coverage and the number of revealed faults. However, \SapienzDiv typically produces longer test sequences and requires more execution time than \Sapienz. Conclusions: The understanding of the search problem obtained by the fitness landscape analysis helped us to find a more suitable configuration of \Sapienz without trial-and-error experiments. By promoting diversity of test suites during the search, improved or at least similar test results in terms of faults and coverage can be achieved.

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arXiv2020

Evolutionary Grammar-Based Fuzzing

A fuzzer provides randomly generated inputs to a targeted software to expose erroneous behavior. To efficiently detect defects, generated inputs should conform to the structure of the input format and thus, grammars can be used to generate syntactically correct inputs. In this context, fuzzing can be guided by probabilities attached to competing rules in the grammar, leading to the idea of probabilistic grammar-based fuzzing. However, the optimal assignment of probabilities to individual grammar rules to effectively expose erroneous behavior for individual systems under test is an open research question. In this paper, we present EvoGFuzz, an evolutionary grammar-based fuzzing approach to optimize the probabilities to generate test inputs that may be more likely to trigger exceptional behavior. The evaluation shows the effectiveness of EvoGFuzz in detecting defects compared to probabilistic grammar-based fuzzing (baseline). Applied to ten real-world applications with common input formats (JSON, JavaScript, or CSS3), the evaluation shows that EvoGFuzz achieved a significantly larger median line coverage for all subjects by up to 48% compared to the baseline. Moreover, EvoGFuzz managed to expose 11 unique defects, from which five have not been detected by the baseline.

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arXiv2020

Bet and Run for Test Case Generation

Anyone working in the technology sector is probably familiar with the question: "Have you tried turning it off and on again?", as this is usually the default question asked by tech support. Similarly, it is known in search based testing that metaheuristics might get trapped in a plateau during a search. As a human, one can look at the gradient of the fitness curve and decide to restart the search, so as to hopefully improve the results of the optimization with the next run. Trying to automate such a restart, it has to be programmatically decided whether the metaheuristic has encountered a plateau yet, which is an inherently difficult problem. To mitigate this problem in the context of theoretical search problems, the Bet and Run strategy was developed, where multiple algorithm instances are started concurrently, and after some time all but the single most promising instance in terms of fitness values are killed. In this paper, we adopt and evaluate the Bet and Run strategy for the problem of test case generation. Our work indicates that use of this restart strategy does not generally lead to gains in the quality metrics, when instantiated with the best parameters found in the literature.

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arXiv2019

Challenges for Verifying and Validating Scientific Software in Computational Materials Science

Many fields of science rely on software systems to answer different research questions. For valid results researchers need to trust the results scientific software produces, and consequently quality assurance is of utmost importance. In this paper we are investigating the impact of quality assurance in the domain of computational materials science (CMS). Based on our experience in this domain we formulate challenges for validation and verification of scientific software and their results. Furthermore, we describe directions for future research that can potentially help dealing with these challenges.

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arXiv2019

Does Diversity Improve the Test Suite Generation for Mobile Applications?

In search-based software engineering we often use popular heuristics with default configurations, which typically lead to suboptimal results, or we perform experiments to identify configurations on a trial-and-error basis, which may lead to better results for a specific problem. To obtain better results while avoiding trial-and-error experiments, a fitness landscape analysis is helpful in understanding the search problem, and making an informed decision about the heuristics. In this paper, we investigate the search problem of test suite generation for mobile applications (apps) using SAPIENZ whose heuristic is a default NSGA-II. We analyze the fitness landscape of SAPIENZ with respect to genotypic diversity and use the gained insights to adapt the heuristic of SAPIENZ. These adaptations result in SAPIENZ^div that aims for preserving the diversity of test suites during the search. To evaluate SAPIENZ^div, we perform a head-to-head comparison with SAPIENZ on 76 open-source apps.

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arXiv2019

Perpetual Assurances for Self-Adaptive Systems

Providing assurances for self-adaptive systems is challenging. A primary underlying problem is uncertainty that may stem from a variety of different sources, ranging from incomplete knowledge to sensor noise and uncertain behavior of humans in the loop. Providing assurances that the self-adaptive system complies with its requirements calls for an enduring process spanning the whole lifetime of the system. In this process, humans and the system jointly derive and integrate new evidence and arguments, which we coined perpetual assurances for self-adaptive systems. In this paper, we provide a background framework and the foundation for perpetual assurances for self-adaptive systems. We elaborate on the concrete challenges of offering perpetual assurances, requirements for solutions, realization techniques and mechanisms to make solutions suitable. We also present benchmark criteria to compare solutions. We then present a concrete exemplar that researchers can use to assess and compare approaches for perpetual assurances for self-adaptation.

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arXiv2018

Inputs from Hell: Generating Uncommon Inputs from Common Samples

Generating structured input files to test programs can be performed by techniques that produce them from a grammar that serves as the specification for syntactically correct input files. Two interesting scenarios then arise for effective testing. In the first scenario, software engineers would like to generate inputs that are as similar as possible to the inputs in common usage of the program, to test the reliability of the program. More interesting is the second scenario where inputs should be as dissimilar as possible from normal usage. This is useful for robustness testing and exploring yet uncovered behavior. To provide test cases for both scenarios, we leverage a context-free grammar to parse a set of sample input files that represent the program's common usage, and determine probabilities for individual grammar production as they occur during parsing the inputs. Replicating these probabilities during grammar-based test input generation, we obtain inputs that are close to the samples. Inverting these probabilities yields inputs that are strongly dissimilar to common inputs, yet still valid with respect to the grammar. Our evaluation on three common input formats (JSON, JavaScript, CSS) shows the effectiveness of these approaches in obtaining instances from both sets of inputs.

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arXiv2015

Using Models at Runtime to Address Assurance for Self-Adaptive Systems

A self-adaptive software system modifies its behavior at runtime in response to changes within the system or in its execution environment. The fulfillment of the system requirements needs to be guaranteed even in the presence of adverse conditions and adaptations. Thus, a key challenge for self-adaptive software systems is assurance. Traditionally, confidence in the correctness of a system is gained through a variety of activities and processes performed at development time, such as design analysis and testing. In the presence of selfadaptation, however, some of the assurance tasks may need to be performed at runtime. This need calls for the development of techniques that enable continuous assurance throughout the software life cycle. Fundamental to the development of runtime assurance techniques is research into the use of models at runtime (M@RT). This chapter explores the state of the art for usingM@RT to address the assurance of self-adaptive software systems. It defines what information can be captured by M@RT, specifically for the purpose of assurance, and puts this definition into the context of existing work. We then outline key research challenges for assurance at runtime and characterize assurance methods. The chapter concludes with an exploration of selected application areas where M@RT could provide significant benefits beyond existing assurance techniques for adaptive systems.

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