Time-Space Efficient Regression Testing for Configurable Systems

Configurable systems are those that can be adapted from a set of options. They are prevalent and testing them is important and challenging. Existing approaches for testing configurable systems are either unsound (i.e., they can miss fault-revealing configurations) or do not scale. This paper proposes EvoSPLat, a regression testing technique for configurable systems. EvoSPLat builds on our previously-developed technique, SPLat, which explores all dynamically reachable configurations from a test. EvoSPLat is tuned for two scenarios of use in regression testing: Regression Configuration Selection (RCS) and Regression Test Selection (RTS). EvoSPLat for RCS prunes configurations (not tests) that are not impacted by changes whereas EvoSPLat for RTS prunes tests (not configurations) which are not impacted by changes. Handling both scenarios in the context of evolution is important. Experimental results show that EvoSPLat is promising. We observed a substantial reduction in time (22%) and in the number of configurations (45%) for configurable Java programs. In a case study on a large real-world configurable system (GCC), EvoSPLat reduced 35% of the running time. Comparing EvoSPLat with sampling techniques, 2-wise was the most efficient technique, but it missed two bugs whereas EvoSPLat detected all bugs four times faster than 6-wise, on average.Comment: 14 page

Efficient Monitoring of ??-languages

We present a technique for generating efficient monitors for Omega-regular-languages. We show how Buchi automata can be reduced in size and transformed into special, statistically optimal nondeterministic finite state machines, called binary transition tree finite state machines (BTT-FSMs), which recognize precisely the minimal bad prefixes of the original omega-regular-language. The presented technique is implemented as part of a larger monitoring framework and is available for download

Monitoring-Oriented Programming: A Tool-Supported Methodology for Higher Quality Object-Oriented Software

This paper presents a tool-supported methodological paradigm for object-oriented software development, called monitoring-oriented programming and abbreviated MOP, in which runtime monitoring is a basic software design principle. The general idea underlying MOP is that software developers insert specifications in their code via annotations. Actual monitoring code is automatically synthesized from these annotations before compilation and integrated at appropriate places in the program, according to user-defined configuration attributes. This way, the specification is checked at runtime against the implementation. Moreover, violations and/or validations of specifications can trigger user-defined code at any points in the program, in particular recovery code, outputting or sending messages, or raising exceptions. The MOP paradigm does not promote or enforce any specific formalism to specify requirements: it allows the users to plug-in their favorite or domain-specific specification formalisms via logic plug-in modules. There are two major technical challenges that MOP supporting tools unavoidably face: monitor synthesis and monitor integration. The former is heavily dependent on the specification formalism and comes as part of the corresponding logic plug-in, while the latter is uniform for all specification formalisms and depends only on the target programming language. An experimental prototype tool, called Java-MOP, is also discussed, which currently supports most but not all of the desired MOP features. MOP aims at reducing the gap between formal specification and implementation, by integrating the two and allowing them together to form a system

The Effects of Computational Resources on Flaky Tests

Flaky tests are tests that nondeterministically pass and fail in unchanged code. These tests can be detrimental to developers' productivity. Particularly when tests run in continuous integration environments, the tests may be competing for access to limited computational resources (CPUs, memory etc.), and we hypothesize that resource (in)availability may be a significant factor in the failure rate of flaky tests. We present the first assessment of the impact that computational resources have on flaky tests, including a total of 52 projects written in Java, JavaScript and Python, and 27 different resource configurations. Using a rigorous statistical methodology, we determine which tests are RAFT (Resource-Affected Flaky Tests). We find that 46.5% of the flaky tests in our dataset are RAFT, indicating that a substantial proportion of flaky-test failures can be avoided by adjusting the resources available when running tests. We report RAFTs and configurations to avoid them to developers, and received interest to either fix the RAFTs or to improve the specifications of the projects so that tests would be run only in configurations that are unlikely to encounter RAFT failures. Our results also have implications for researchers attempting to detect flaky tests, e.g., reducing the resources available when running tests is a cost-effective approach to detect more flaky failures.Comment: This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

Compositional Solution Space Quantification for Probabilistic Software Analysis

Probabilistic software analysis aims at quantifying how likely a target event is to occur during program execution. Current approaches rely on symbolic execution to identify the conditions to reach the target event and try to quantify the fraction of the input domain satisfying these conditions. Precise quantification is usually limited to linear constraints, while only approximate solutions can be provided in general through statistical approaches. However, statistical approaches may fail to converge to an acceptable accuracy within a reasonable time. We present a compositional statistical approach for the efficient quantification of solution spaces for arbitrarily complex constraints over bounded floating-point domains. The approach leverages interval constraint propagation to improve the accuracy of the estimation by focusing the sampling on the regions of the input domain containing the sought solutions. Preliminary experiments show significant improvement on previous approaches both in results accuracy and analysis time

Avaliação da microbiota associada à Pseudolynchia canariensis coletadas em pombos domésticos (Columba livia)

Pombos domésticos ( Columba livia) são frequentemente encontrados em ambientes urbanos e carreiam grandes quantidades de microrganismos como bactérias (família Enterobacteriaceae) e fungos (Cryptococcus, Histoplasma e Candida), sendo alguns deles causadores de doença em humanos. Entre as penas desses hospedeiros, vive a mosca chamada Pseudolynchia canariensis (Diptera: Hippoboscidae), um inseto hematófago que pode albergar micro-organismos patogênicos ao homem. O objetivo deste estudo foi pesquisar a flora normal associada à P. canariensis coletada em pombos urbanos encontrados nos prédios da Universidade Federal do Triângulo Mineiro (UFTM). Foram capturados 30 pombos, dos quais foram coletados P. canariensis. Foi realizada pesquisa para isolamento de bactérias e fungos das pernas e peças bucais dos insetos. Grande número de espécies de microorganismos foi detectado, algumas delas patogênicas aos seres humanos, como as bactérias Escherichia coli, Streptococcus, Staphylococcus, Pseudomonas e Bacillus spp e os fungos Aspergillus sp., Candida parapsilosis, Fusarium sp., Penicillium sp. e Trichophyton sp. Pela primeira vez se descreve a presença desses microorganismos associadas aos pombos domésticos e seus ectoparasitas, sugerindo risco às pessoas que frequentam os prédios da UFTM, visto que os pombos, bem como a P. canariensis, podem ser fontes de agentes infecciosos

An Equational Specification for the Scheme Language

This work describes the formal semantics of Scheme (Based on the publicly available report R5RS) as an equational theory in the Maude rewriting system. The semantics is based on continuations and is highly modular. We briefly investigate the relationship between our methodology for defining programming languages and other semantic formalisms. We conclude by showing some performance results of the interpreter obtained for free from the executable specification