445,809 research outputs found

    An automated Model-based Testing Approach in Software Product Lines Using a Variability Language.

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    This paper presents the application of an automated testing approach for Software Product Lines (SPL) driven by its state-machine and variability models. Context: Model-based testing provides a technique for automatic generation of test cases using models. Introduction of a variability model in this technique can achieve testing automation in SPL. Method: We use UML and CVL (Common Variability Language) models as input, and JUnit test cases are derived from these models. This approach has been implemented using the UML2 Eclipse Modeling platform and the CVL-Tool. Validation: A model checking tool prototype has been developed and a case study has been performed. Conclusions: Preliminary experiments have proved that our approach can find structural errors in the SPL under test. In our future work we will introduce Object Constraint Language (OCL) constraints attached to the input UML mode

    Colored model based testing for software product lines (CMBT-SWPL)

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    Over the last decade, the software product line domain has emerged as one of the mostpromising software development paradigms. The main beneïŹts of a software product lineapproach are improvements in productivity, time to market, product quality, and customersatisfaction.Therefore, one topic that needs greater emphasis is testing of software product lines toachieve the required software quality assurance. Our concern is how to test a softwareproduct line as early as possible in order to detect errors, because the cost of error detectedIn early phases is much less compared to the cost of errors when detected later.The method suggested in this thesis is a model-based, reuse-oriented test technique calledColored Model Based Testing for Software Product Lines (CMBT-SWPL). CMBT-SWPLis a requirements-based approach for eïŹƒciently generating tests for products in a soft-ware product line. This testing approach is used for validation and veriïŹcation of productlines. It is a novel approach to test product lines using a Colored State Chart (CSC), whichconsiders variability early in the product line development process. More precisely, the vari-ability will be introduced in the main components of the CSC. Accordingly, the variabilityis preserved in test cases, as they are generated from colored test models automatically.During domain engineering, the CSC is derived from the feature model. By coloring theState Chart, the behavior of several product line variants can be modeled simultaneouslyin a single diagram and thus address product line variability early. The CSC representsthe test model, from which test cases using statistical testing are derived.During application engineering, these colored test models are customized for a speciïŹcapplication of the product line. At the end of this test process, the test cases are generatedagain using statistical testing, executed and the test results are ready for evaluation. Inxaddition, the CSC will be transformed to a Colored Petri Net (CPN) for veriïŹcation andsimulation purposes.The main gains of applying the CMBT-SWPL method are early detection of defects inrequirements, such as ambiguities incompleteness and redundancy which is then reïŹ‚ectedin saving the test eïŹ€ort, time, development and maintenance costs

    A systematic review of quality attributes and measures for software product lines

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    [EN] It is widely accepted that software measures provide an appropriate mechanism for understanding, monitoring, controlling, and predicting the quality of software development projects. In software product lines (SPL), quality is even more important than in a single software product since, owing to systematic reuse, a fault or an inadequate design decision could be propagated to several products in the family. Over the last few years, a great number of quality attributes and measures for assessing the quality of SPL have been reported in literature. However, no studies summarizing the current knowledge about them exist. This paper presents a systematic literature review with the objective of identifying and interpreting all the available studies from 1996 to 2010 that present quality attributes and/or measures for SPL. These attributes and measures have been classified using a set of criteria that includes the life cycle phase in which the measures are applied; the corresponding quality characteristics; their support for specific SPL characteristics (e. g., variability, compositionality); the procedure used to validate the measures, etc. We found 165 measures related to 97 different quality attributes. The results of the review indicated that 92% of the measures evaluate attributes that are related to maintainability. In addition, 67% of the measures are used during the design phase of Domain Engineering, and 56% are applied to evaluate the product line architecture. However, only 25% of them have been empirically validated. In conclusion, the results provide a global vision of the state of the research within this area in order to help researchers in detecting weaknesses, directing research efforts, and identifying new research lines. In particular, there is a need for new measures with which to evaluate both the quality of the artifacts produced during the entire SPL life cycle and other quality characteristics. There is also a need for more validation (both theoretical and empirical) of existing measures. In addition, our results may be useful as a reference guide for practitioners to assist them in the selection or the adaptation of existing measures for evaluating their software product lines. © 2011 Springer Science+Business Media, LLC.This research has been funded by the Spanish Ministry of Science and Innovation under the MULTIPLE (Multimodeling Approach For Quality-Aware Software Product Lines) project with ref. TIN2009-13838.Montagud Gregori, S.; Abrahao Gonzales, SM.; InsfrĂĄn Pelozo, CE. (2012). A systematic review of quality attributes and measures for software product lines. Software Quality Journal. 20(3-4):425-486. https://doi.org/10.1007/s11219-011-9146-7S425486203-4Abdelmoez, W., Nassar, D. M., Shereschevsky, M., Gradetsky, N., Gunnalan, R., Ammar, H. H., et al. (2004). Error propagation in software architectures. In 10th international symposium on software metrics (METRICS), Chicago, Illinois, USA.Ajila, S. A., & Dumitrescu, R. T. (2007). Experimental use of code delta, code churn, and rate of change to understand software product line evolution. Journal of Systems and Software, 80, 74–91.Aldekoa, G., Trujillo, S., Sagardui, G., & DĂ­az, O. (2006). Experience measuring maintainability in software product lines. In XV Jornadas de IngenierĂ­a del Software y Bases de Datos (JISBD). Barcelona.Aldekoa, G., Trujillo, S., Sagardui, G., & DĂ­az, O. (2008). Quantifying maintanibility in feature oriented product lines, Athens, Greece, pp. 243–247.Alves de Oliveira Junior, E., Gimenes, I. M. S., & Maldonado, J. C. (2008). A metric suite to support software product line architecture evaluation. In XXXIV Conferencia Latinamericana de InformĂĄtica (CLEI), Santa FĂ©, Argentina, pp. 489–498.Alves, V., Niu, N., Alves, C., & Valença, G. (2010). Requirements engineering for software product lines: A systematic literature review. Information & Software Technology, 52(8), 806–820.Bosch, J. (2000). Design and use of software architectures: Adopting and evolving a product line approach. USA: ACM Press/Addison-Wesley Publishing Co.Briand, L. C., Differing, C. M., & Rombach, D. (1996a). Practical guidelines for measurement-based process improvement. Software Process-Improvement and Practice, 2, 253–280.Briand, L. C., Morasca, S., & Basili, V. R. (1996b). Property based software engineering measurement. IEEE Transactions on Software Eng., 22(1), 68–86.Calero, C., Ruiz, J., & Piattini, M. (2005). Classifying web metrics using the web quality model. Online Information Review, 29(3): 227–248.Chen, L., Ali Babar, M., & Ali, N. (2009). Variability management in software product lines: A systematic review. In 13th international software product lines conferences (SPLC), San Francisco, USA.Clements, P., & Northrop, L. (2002). Software product lines. 2003. Software product lines practices and patterns. Boston, MA: Addison-Wesley.Crnkovic, I., & Larsson, M. (2004). Classification of quality attributes for predictability in component-based systems. Journal of Econometrics, pp. 231–250.Conference Rankings of Computing Research and Education Association of Australasia (CORE). (2010). Available in http://core.edu.au/index.php/categories/conference%20rankings/1 .Davis, A., Dieste, Ó., Hickey, A., Juristo, N., & Moreno, A. M. (2006). Effectiveness of requirements elicitation techniques: Empirical results derived from a systematic review. In 14th IEEE international conference requirements engineering, pp. 179–188.de Souza Filho, E. D., de Oliveira Cavalcanti, R., Neiva, D. F. S., Oliveira, T. H. B., Barachisio Lisboa, L., de Almeida E. S., & de Lemos Meira, S. R. (2008). Evaluating domain design approaches using systematic review. In 2nd European conference on software architecture, Cyprus, pp. 50–65.Ejiogu, L. (1991). Software engineering with formal metrics. QED Publishing.Engström, E., & Runeson, P. (2011). Software product line testing—A systematic mapping study. Information & Software Technology, 53(1), 2–13.Etxeberria, L., Sagarui, G., & Belategi, L. (2008). Quality aware software product line engineering. Journal of the Brazilian Computer Society, 14(1), Campinas Mar.Ganesan, D., Knodel, J., Kolb, R., Haury, U., & Meier, G. (2007). Comparing costs and benefits of different test strategies for a software product line: A study from Testo AG. In 11th international software product line conference, Kyoto, Japan, pp. 74–83, September 2007.GĂłmez, O., Oktaba, H., Piattini, M., & GarcĂ­a, F. (2006). A systematic review measurement in software engineering: State-of-the-art in measures. In First international conference on software and data technologies (ICSOFT), SetĂșbal, Portugal, pp. 11–14.IEEE standard for a software quality metrics methodology, IEEE Std 1061-1998, 1998.Inoki, M., & Fukazawa, Y. (2007). Software product line evolution method based on Kaizen approach. In 22nd annual ACM symposium on applied computing, Korea.Insfran, E., & Fernandez, A. (2008). A systematic review of usability evaluation in Web development. 2nd international workshop on web usability and accessibility (IWWUA’08), New Zealand, LNCS 5176, Springer, pp. 81–91.ISO/IEC 25010. (2008). Systems and software engineering. Systems and software Quality Requirements and Evaluation (SQuaRE). System and software quality models.ISO/IEC 9126. (2000). Software engineering. Product Quality.Johansson, E., & Höst, R. (2002). Tracking degradation in software product lines through measurement of design rule violations. In 14th International conference on software engineering and knowledge engineering, Ischia, Italy, pp. 249–254.Journal Citation Reports of Thomson Reuters. (2010). Available in http://thomsonreuters.com/products_services/science/science_products/a-z/journal_citation_reports/ .Khurum, M., & Gorschek, T. (2009). A systematic review of domain analysis solutions for product lines. The Journal of Systems and Software.Kim, T., Ko, I. Y., Kang, S. W., & Lee, D. H. (2008). Extending ATAM to assess product line architecture. In 8th IEEE international conference on computer and information technology, pp. 790–797.Kitchenham, B. (2007). Guidelines for performing systematic literature reviews in software engineering. Version 2.3, EBSE Technical Report, Keele University, UK.Kitchenham, B., Pfleeger, S., & Fenton, N. (1995). Towards a framework for software measurement validation. IEEE Transactions on Software Engineering, 21(12).Landis, J. R., & Koch, G. G. (1977). The measurement of observer agreement for categorical data. Biometrics, 33, 159–174.Mendes, E. (2005). A systematic review of Web engineering research. International symposium on empirical software engineering. Noosa Heads, Australia.Meyer, M. H., & Dalal, D. (2002). Managing platform architectures and manufacturing processes for non assembled products. Journal of Product Innovation Management, 19(4), 277–293.Montagud, S., & AbrahĂŁo, S. (2009). Gathering Current knowledge about quality evaluation in software product lines. In 13th international software product lines conferences (SPLC), San Francisco, USA.Montagud, S., & AbrahĂŁo, S. (2009). A SQuaRE-bassed quality evaluation method for software product lines. Master’s thesis, December 2009 (in Spanish).Needham, D., & Jones, S. (2006). A software fault tree metric. In 22nd international conference on software maintenance (ICSM), Philadelphia, Pennsylvania, USA.NiemelĂ€, E., & Immonen, A. (2007). Capturing quality requirements of product family architecture. Information and Software Technology, 49(11–12), 1107–1120.Odia, O. E. (2007). Testing in software product lines. Master Thesis Software Engineering of School of Engineering, Bleking Institute of Technology. Thesis no. MSE-2007:16, Sweden.Olumofin, F. G., & MiĆĄić, V. B. (2007). A holistic architecture assessment method for software product lines. Information and Software Technology, 49, 309–323.PĂ©rez Lamancha, B., Polo Usaola, M., & Piattini Velthius, M. (2009). Software product line testing—a systematic review. ICSOFT, (1), 23–30.Poels, G., & Dedene, G. (2000). Distance-based software measurement: necessary and sufficient properties for software measures. Information and Software Technology, 42(I), 35–46.Prehofer, C., van Gurp, J., & Bosch, J. (2008). Compositionality in software platforms. In Emerging methods, technologies and process management in software engineering. Wiley.Rahman, A. (2004). Metrics for the structural assessment of product line architecture. Master Thesis on Software Engineering, Thesis no. MSE-2004:24. School of Engineering, Blekinge Institute of Technology, Sweden.Sethi, K., Cai, Y., Wong, S., Garcia, A., & Sant’Anna, C. (2009). From retrospect to prospect: Assessing modularity and stability from software architecture. Joint working IEEE/IFIP conference on software architecture, 2009 & European conference on software architecture. WICSA/ECSA.Shaik, I., Abdelmoez, W,. Gunnalan, R., Shereshevsky, M., Zeid, A., Ammar, H. H., et al. (2005). Change propagation for assessing design quality of software architectures. 5th working IEEE/IFIP conference on software architecture (WICSA’05).Siegmund, N., RosenmĂŒller, M., Kuhlemann, M., KĂ€stner, C., & Saake, G. (2008). Measuring non-functional properties in software product lines for product derivation. In 15th Asia-Pacific software engineering conference, Beijing, China.Sun Her, J., Hyeok Kim, J., Hun Oh, S., Yul Rhew, S., & Dong Kim, S. (2007). A framework for evaluating reusability of core asset in product line engineering. Information and Software Technology, 49, 740–760.Svahnberg, M., & Bosch, J. (2000). Evolution in software product lines. In 3rd international workshop on software architectures for products families (IWSAPF-3). Las Palmas de Gran Canaria.Van der Hoek, A., Dincel, E., & Medidović, N. (2003). Using services utilization metrics to assess the structure of product line architectures. In 9th international software metrics symposium (METRICS), Sydney, Australia.Van der Linden, F., Schmid, K., & Rommes, E. (2007). Software product lines in action. Springer.Whitmire, S. (1997). Object oriented design measurement. John Wiley & Sons.Wnuk, K., Regnell, B., & Karlsson, L. (2009). What happened to our features? Visualization and understanding of scope change dynamics in a large-scale industrial setting. In 17th IEEE international requirements engineering conference.Yoshimura, K., Ganesan, D., & Muthig, D. (2006). Assessing merge potential of existing engine control systems into a product line. In International workshop on software engineering for automative systems, Shangai, China, pp. 61–67.Zhang, T., Deng, L., Wu, J., Zhou, Q., & Ma, C. (2008). Some metrics for accessing quality of product line architecture. In International conference on computer science and software engineering (CSSE), Wuhan, China, pp. 500–503

    Black-Box Testfall-Selektion und -Priorisierung fĂŒr Software-Varianten und -Versionen

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    Software testing is a fundamental task in software quality assurance. Especially when dealing with several product variants or software versions under test, testing everything for each variant and version is infeasible due to limited testing resources. To cope with increasing complexity both in time (i.e., versions) and space (i.e., variants), new techniques have to be developed to focus on the most important parts for testing. In the past, regression testing techniques such as test case selection and prioritization have emerged to tackle these issues for single-software systems. However, testing of variants and versions is still a challenging task, especially when no source code is available. Most existing regression testing techniques analyze source code to identify important changes to be retested, i.e., they are likely to reveal a failure. To this end, this thesis contributes different techniques for both, variants and versions, to allow more efficient and effective testing in difficult black-box scenarios by identifying important test cases to be re-executed. Four major contributions in software testing are made. (1) We propose a test case prioritization framework for software product lines based on delta-oriented test models to reduce the redundancy in testing between different product variants.(2) We introduce a risk-based testing technique for software product lines. Our semi-automatic test case prioritization approach is able to compute risk values for test model elements and scales with large numbers of product variants. (3) For black-box software versions, we provide a test case selection technique based on genetic algorithms. In particular, seven different black-box selection objectives are defined, thus, we perform a multi-objective test case selection finding Pareto optimal test sets to reduce the testing effort. (4) We propose a novel test case prioritization technique based on supervised machine learning. It is able to imitate decisions made by experts based on different features, such as natural language test case descriptions and black-box meta-data. All of these techniques have been evaluated using the Body Comfort System case study. For testing of software versions, we also assesses our testing techniques using an industrial system. Our evaluation results indicate that our black-box testing approaches for software variants and versions are able to successfully reduce testing effort compared to existing techniques.Testen ist eine fundamentale Aufgabe zur QualitĂ€tssicherung von modernen Softwaresystemen. Mangels limitierter Ressourcen ist das Testen von vielen Produktvarianten oder Versionen sehr herausfordernd und das wiederholte AusfĂŒhren aller TestfĂ€lle nicht wirtschaftlich. Um mit der Raum- (Varianten) und Zeitdimension (Versionen) in der Entwicklung umzugehen, wurden in der Vergangenheit verschiedene TestansĂ€tze entwickelt. Es existieren jedoch nach wie vor große Herausforderungen, welche es zu lösen gilt. Dies ist vor allem der Fall, wenn der Quellcode der getesteten Softwaresysteme unbekannt ist. Das Testen von Black-Box-Systemen erschwert die Identifikation von zu testenden Unterschieden zu vorher getesteten Varianten oder Versionen. In der Literatur finden sich wenige AnsĂ€tze, welche versuchen diese Herausforderungen zu lösen. Daher werden in dieser Dissertation neue AnsĂ€tze entwickelt und vorgestellt, welche beim Black-Box Testen von Software-Varianten und -Versionen helfen, wichtige TestfĂ€lle zur erneuten AusfĂŒhrung zu identifizieren. Dies erspart die AusfĂŒhrung von TestfĂ€llen, welche weder neues Verhalten testen noch mit hoher Wahrscheinlichkeit neue Fehler zu finden. Insgesamt leistet diese Dissertation die folgenden vier wissenschaftlichen BeitrĂ€ge: (1) Ein modell-basiertes Framework zur Definition von Testfallpriorisierungsfunktionen fĂŒr variantenreiche Systeme. Das Framework ermöglicht eine flexible Priorisierung von TestfĂ€llen fĂŒr individuelle Produktvarianten. (2) Einen risiko-basierten Testfallpriorisierungsansatz fĂŒr variantenreiche Systeme. Das Verfahren ermöglicht eine semi-automatisierte Berechnung von Risikowerten fĂŒr Elemente von Produktvarianten und skaliert mit großen Produktzahlen. (3) Ein multi-kriterielles Testfallselektionsverfahren fĂŒr den Regressionstest von Black-Box Software-Versionen. Es werden Black-Box Testkriterien aufgestellt und mittels eines genetischen Algorithmus optimiert um Pareto-optimale Testsets zu berechnen. (4) Ein Testfallpriorisierungsverfahren fĂŒr Black-Box Regressionstests mit Hilfe von Machine Learning. Der verwendete Algorithmus imitiert Entscheidungen von Testexperten um wichtige TestfĂ€lle zu identifizieren. Diese AnsĂ€tze wurden alle mit Hilfe von Fallstudien evaluiert. Die resultierenden Ergebnisse zeigen, dass die AnsĂ€tze die gewĂŒnschten Ziele erreichen und helfen, wichtige TestfĂ€lle effektiv zu identifizieren. Insgesamt wird der Testaufwand im Vergleich zu existierenden Techniken verringert

    Towards Statistical Prioritization for Software Product Lines Testing

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    Software Product Lines (SPL) are inherently difficult to test due to the combinatorial explosion of the number of products to consider. To reduce the number of products to test, sampling techniques such as combinatorial interaction testing have been proposed. They usually start from a feature model and apply a coverage criterion (e.g. pairwise feature interaction or dissimilarity) to generate tractable, fault-finding, lists of configurations to be tested. Prioritization can also be used to sort/generate such lists, optimizing coverage criteria or weights assigned to features. However, current sampling/prioritization techniques barely take product behavior into account. We explore how ideas of statistical testing, based on a usage model (a Markov chain), can be used to extract configurations of interest according to the likelihood of their executions. These executions are gathered in featured transition systems, compact representation of SPL behavior. We discuss possible scenarios and give a prioritization procedure illustrated on an example.Comment: Extended version published at VaMoS '14 (http://dx.doi.org/10.1145/2556624.2556635

    Hybrid Algorithms Based on Integer Programming for the Search of Prioritized Test Data in Software Product Lines

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    In Software Product Lines (SPLs) it is not possible, in general, to test all products of the family. The number of products denoted by a SPL is very high due to the combinatorial explosion of features. For this reason, some coverage criteria have been proposed which try to test at least all feature interactions without the necessity to test all products, e.g., all pairs of features (pairwise coverage). In addition, it is desirable to first test products composed by a set of priority features. This problem is known as the Prioritized Pairwise Test Data Generation Problem. In this work we propose two hybrid algorithms using Integer Programming (IP) to generate a prioritized test suite. The first one is based on an integer linear formulation and the second one is based on a integer quadratic (nonlinear) formulation. We compare these techniques with two state-of-the-art algorithms, the Parallel Prioritized Genetic Solver (PPGS) and a greedy algorithm called prioritized-ICPL. Our study reveals that our hybrid nonlinear approach is clearly the best in both, solution quality and computation time. Moreover, the nonlinear variant (the fastest one) is 27 and 42 times faster than PPGS in the two groups of instances analyzed in this work.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂ­a Tech. Partially funded by the Spanish Ministry of Economy and Competitiveness and FEDER under contract TIN2014-57341-R, the University of MĂĄlaga, AndalucĂ­a Tech and the Spanish Network TIN2015-71841-REDT (SEBASENet)

    Potential Errors and Test Assessment in Software Product Line Engineering

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    Software product lines (SPL) are a method for the development of variant-rich software systems. Compared to non-variable systems, testing SPLs is extensive due to an increasingly amount of possible products. Different approaches exist for testing SPLs, but there is less research for assessing the quality of these tests by means of error detection capability. Such test assessment is based on error injection into correct version of the system under test. However to our knowledge, potential errors in SPL engineering have never been systematically identified before. This article presents an overview over existing paradigms for specifying software product lines and the errors that can occur during the respective specification processes. For assessment of test quality, we leverage mutation testing techniques to SPL engineering and implement the identified errors as mutation operators. This allows us to run existing tests against defective products for the purpose of test assessment. From the results, we draw conclusions about the error-proneness of the surveyed SPL design paradigms and how quality of SPL tests can be improved.Comment: In Proceedings MBT 2015, arXiv:1504.0192

    Automated analysis of feature models: Quo vadis?

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    Feature models have been used since the 90's to describe software product lines as a way of reusing common parts in a family of software systems. In 2010, a systematic literature review was published summarizing the advances and settling the basis of the area of Automated Analysis of Feature Models (AAFM). From then on, different studies have applied the AAFM in different domains. In this paper, we provide an overview of the evolution of this field since 2010 by performing a systematic mapping study considering 423 primary sources. We found six different variability facets where the AAFM is being applied that define the tendencies: product configuration and derivation; testing and evolution; reverse engineering; multi-model variability-analysis; variability modelling and variability-intensive systems. We also confirmed that there is a lack of industrial evidence in most of the cases. Finally, we present where and when the papers have been published and who are the authors and institutions that are contributing to the field. We observed that the maturity is proven by the increment in the number of journals published along the years as well as the diversity of conferences and workshops where papers are published. We also suggest some synergies with other areas such as cloud or mobile computing among others that can motivate further research in the future.Ministerio de EconomĂ­a y Competitividad TIN2015-70560-RJunta de AndalucĂ­a TIC-186

    Automated metamorphic testing on the analyses of feature models

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    Copyright © 2010 Elsevier B.V. All rights reserved.Context: A feature model (FM) represents the valid combinations of features in a domain. The automated extraction of information from FMs is a complex task that involves numerous analysis operations, techniques and tools. Current testing methods in this context are manual and rely on the ability of the tester to decide whether the output of an analysis is correct. However, this is acknowledged to be time-consuming, error-prone and in most cases infeasible due to the combinatorial complexity of the analyses, this is known as the oracle problem.Objective: In this paper, we propose using metamorphic testing to automate the generation of test data for feature model analysis tools overcoming the oracle problem. An automated test data generator is presented and evaluated to show the feasibility of our approach.Method: We present a set of relations (so-called metamorphic relations) between input FMs and the set of products they represent. Based on these relations and given a FM and its known set of products, a set of neighbouring FMs together with their corresponding set of products are automatically generated and used for testing multiple analyses. Complex FMs representing millions of products can be efficiently created by applying this process iteratively.Results: Our evaluation results using mutation testing and real faults reveal that most faults can be automatically detected within a few seconds. Two defects were found in FaMa and another two in SPLOT, two real tools for the automated analysis of feature models. Also, we show how our generator outperforms a related manual suite for the automated analysis of feature models and how this suite can be used to guide the automated generation of test cases obtaining important gains in efficiency.Conclusion: Our results show that the application of metamorphic testing in the domain of automated analysis of feature models is efficient and effective in detecting most faults in a few seconds without the need for a human oracle.This work has been partially supported by the European Commission(FEDER)and Spanish Government under CICYT project SETI(TIN2009-07366)and the Andalusian Government project ISABEL(TIC-2533)
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