Previous studies have shown the negative effects that low-quality code can have on maintainability proxies, such as code change- and defect-proneness. One of the symptoms for low-quality code are code smells, defined as sub-optimal implementation choices. While this definition is quite general and seems to suggest a wide spectrum of smells that can affect software systems, the research literature mostly focuses on the set of smells defined in the catalogue by Fowler and Beck, reporting design issues that can potentially affect any kind of system, regardless of their architecture (eg Complex Class). However, systems adopting a specific architecture (eg the Model-View-Controller pattern) can be affected by other types of poor practices that only manifest themselves in the chosen architecture. We present a catalogue of six smells tailored to MVC applications and defined by surveying/interviewing 53 MVC developers. We validate our catalogue from different perspectives. First, we assess the relationship between the defined smells and the code change- and defect-proneness. Second, we investigate when these smells are introduced and how long they survive. Third, we survey 21 developers to verify their perception of the defined smells. Fourth, since our catalogue has been mainly defined together with developers adopting a specific Java framework in their MVC applications (eg Spring), we interview four expert developers working with different technologies for the implementation of their MVC applications to check the generalizability of our catalogue. The achieved results show that the defined Web MVC smells (i) more often than not, have more chances of being subject to changes and defects, (ii) are mostly introduced when the affected file (ie the file containing the smell) is committed for the first time in the repository and survive for long time in the system, (iii) are perceived by developers as severe problems, and (iv) generalize to other languages/frameworks.@en

Code smells are symptoms of poor design and implementation choices that may hinder code comprehensibility and maintainability. Despite the effort devoted by the research community in studying code smells, the extent to which code smells in software systems affect software maintainability remains still unclear. In this paper we present a large scale empirical investigation on the diffuseness of code smells and their impact on code change- and fault-proneness. The study was conducted across a total of 395 releases of 30 open source projects and considering 17,350 manually validated instances of 13 different code smell kinds. The results show that smells characterized by long and/or complex code (e.g., Complex Class) are highly diffused, and that smelly classes have a higher change- and fault-proneness than smell-free classes.

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Nine rising stars in software engineering describe how software engineering research will evolve, highlighting emerging opportunities and groundbreaking solutions. They predict the rise of end-user programming, the monitoring of developers through neuroimaging and biometrics sensors, analysis of data from unstructured documents, the mining of mobile marketplaces, and changes to how we create and release software.@en

Code smells are symptoms of poor design and implementation choices that may hinder code comprehension, and possibly increase change-and defect-proneness. A vast catalogue of smells has been defined in the literature, and it includes smells that can be found in any kind of system (e.g., God Classes), regardless of their architecture. On the other hand, software systems adopting specific architectures (e.g., the Model-View-Controller pattern) can be also affected by other types of poor practices. We surveyed and interviewed 53 MVC developers to collect bad practices to avoid while working on Web MVC applications. Then, we followed an open coding procedure on the collected answers to define a catalogue of six Web MVC smells, namely Brain Repository, Fat Repository, Promiscuous Controller, Brain Controller, Laborious Repository Method, and Meddling Service. Then, we ran a study on 100 MVC projects to assess the impact of these smells on code change-and defect-proneness. In addition, we surveyed 21 developers to verify their perception of the defined smells. The achieved results show that the Web MVC smells (i) more often than not, increase change-and defect-proneness of classes, and (ii) are perceived by developers as severe problems.@en