The impact of attractiveness on job opportunities in Italy: a gender field experiment

none3This paper assesses the impact of being attractive and not being native on the gender gap in the opportunity of obtaining a job in Italy. To do so, we propose a field experiment that consists in sending 9680 fictitious curricula vitae to real firms looking for employees. We estimate an Heckit model in order to consider different response from firms and then to calculate the probability to receive a callback. We show that gender gap in opportunity of receiving a callback is a very important issue and this gap is affected by interaction with both attractiveness and not being italian natives, especially for the most qualified jobs.Pubblicazione online open access agosto 2020. Pubblicazione cartacea 2021openBusetta, Giovanni; Fiorillo, Fabio; Palomba, GiulioBusetta, Giovanni; Fiorillo, Fabio; Palomba, Giuli

Code smells: relevance of the problem and novel detection techniques

2015 - 2016Software systems are becoming the core of the business of several industrial companies and, for this reason, they are getting bigger and more complex. Furthermore, they are subject of frantic modifications every day with regard to the implementation of new features or for bug fixing activities. In this context, often developers have not the possibility to design and implement ideal solutions, leading to the introduction of technical debt, i.e., “not quite right code which we postpone making it right”. One noticeable symptom of technical debt is represented by the bad code smells, which were defined by Fowler to indicate sub-optimal design choices applied in the source code by developers. In the recent past, several studies have demonstrated the negative impact of code smells on the maintainability of the source code, as well as on the ability of developers to comprehend a software system. This is the reason why several automatic techniques and tools aimed at discovering portions of code affected by design flaws have been devised. Most of them rely on the analysis of the structural properties (e.g., method calls) mined from the source code. Despite the effort spent by the research community in recent years, there are still limitations that threat the industrial applicability of tools for detecting code smells. Specifically, there is a lack of evicence regarding (i) the circustamces leading to code smell introduction, (ii) the real impact of code smells on maintainability, since previous studies focused the attention on a limited number of software projects. Moreover, existing code smell detectors might be inadeguate for the detection of many code smells defined in literature. For instance, a number xi of code smells are intrinsically characterized by how code elements change over time, rather than by structural properties extractable from the source code. In the context of this thesis we face these specific challenges, by proposing a number of large-scale empirical investigations aimed at understanding (i) when and why smells are actually introduced, (ii) what is their longevity and the way developers remove them in practice, (iii) what is the impact of code smells on change- and fault-proneness, and (iv) how developers perceive code smells. At the same time, we devise two novel approaches for code smell detection that rely on alternative sources of information, i.e., historical and textual, and we evaluate and compare their ability in detecting code smells with respect to other existing baseline approaches solely relying structural analysis. The findings reported in this thesis somehow contradicts common expectations. In the first place, we demonstrate that code smells are usually introduced during the first commit on the repository involving a source file, and therefore they are not the result of frequent modifications during the history of source code. More importantly, almost 80% of the smells survive during the evolution, and the number of refactoring operations performed on them is dramatically low. Of these, only a small percentage actually removed a code smell. At the same time, we also found that code smells have a negative impact on maintainability, and in particular on both change- and fault-proneness of classes. In the second place, we demonstrate that developers can correctly perceive only a subset of code smells characterized by long or complex code, while the perception of other smells depend on the intensity with which they manifest themselves. Furthermore, we also demonstrate the usefulness of historical and textual analysis as a way to improve existing detectors using orthogonal informations. The usage of these alternative sources of information help developers in correctly diagnose design problems and, therefore, they should be actively exploited in future research in the field. Finally, we provide a set of open issues that need to be addressed by the research community in the future, as well as an overview of further future applications of code smells in other software engineering field. [edited by author]I sistemi software stanno diventando il cuore delle attivit`a di molte aziende e, per questa ragione, sono sempre pi `u grandi e complessi. Inoltre, sono frequentemente soggetti a modifiche che riguardano l’implementazione di nuove funzionalit`a o la risoluzione di difetti. In questo contesto, spesso gli sviluppatori non hanno la possibilit`a di progettare ed implementare soluzioni ideali, introducendo quindi technical debt, ovvero codice non ben progettato, la cui ri-progettazione viene postposta nel futuro. Un notevole sintomo della presenza di technical debt `e rappresentato dai bad code smell, che sono stati definiti da Fowler per indicare scelte di progettazione e/o implementazione sub-ottimali applicati dai programmatori durante lo sviluppo di un progetto software. Nel recente passato, molti studi hanno dimostrato l’impatto negativo dei code smell sulla manutenibilit`a e comprensibilit`a del codice sorgente. Per questa ragione, molte tecniche sono state proposte per l’identificazione di porzioni di codice affetto da problemi di progettazione. Molte di queste tecniche si basano sull’analisi delle propriet strutturali (ad esempio, chiamate a metodi esterni) estraibili dal codice sorgente. Nonostante lo sforzo che la comunit`a di ricerca ha profuso negli anni recenti, ci sono ancora limitazioni che precludono l’applicabilit`a industriale di tool per l’identificazione di smell. Nello specifico, c’`e una mancanza di evidenza empirica riguardo (i) le circostanze che portano all’introduzione degli smell, e (ii) il reale impatto degli smell sulla manutenibilit`a, in quanto studi precedenti hanno focalizzato l’attenzione su un numero limitato di progetti software. Inoltre, le tecii niche esistenti per l’identificazione di smell sono inadeguate per quanto concerne l’identificazione di molti dei code smell definiti in letteratura. Ad esempio, molti code smell sono intrinsecamente caratterizzati da come gli elementi nel codice cambiano nel tempo, piuttosto che da propriet`a strutturali estraibili dal codice sorgente. Nel contesto di questa tesi abbiamo affrontato queste sfide specifiche, proponendo diversi studi empirici su larga scala aventi come obiettivo quello di capire (i) quando e perch`e i code smell sono realmente introdotti, (ii) qual `e la loro longevit`a e come gli sviluppatori li rimuovono, (iii) qual `e l’impatto degli smell sulla propensione ai difetti e ai cambiamenti, e (iv) come gli sviluppatori percepiscono gli smell. Allo stesso tempo, abbiamo proposto due nuovi approcci per la rilevazione di code smell che si basano sull’utilizzo di sorgenti alternative di informazioni, ovvero storiche e testuali, e abbiamo valutato e confrontato la loro capacit`a nella identificazione rispetto alle altre tecniche basate su analisi strutturale. I risultati riportati in questa tesi contraddicono le aspettative comuni. Ad esempio, abbiamo dimostrato che i code smell sono spesso introdotti durante il primo commit che introduce l’artefatto affetto dal problema di progettazione. Dall’altro lato, abbiamo dimostrato l’utilit`a dell’analisi storica e testuale come un modo aggiuntivo per migliorare tecniche esistenti con informazioni ortogonali. Inoltre, forniamo un insieme di problemi aperti che necessitato di ulteriore attenzione in futuro, cos`ı come una panoramica di ulteriori applicazioni future dei code smell in altri contesti nel campo dell’ingegneria del software. [a cura dell'autore]XV n.s

Guest Editorial: Special issue on software engineering for mobile applications

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch

A survey on software coupling relations and tools

Context Coupling relations reflect the dependencies between software entities and can be used to assess the quality of a program. For this reason, a vast amount of them has been developed, together with tools to compute their related metrics. However, this makes the coupling measures suitable for a given application challenging to find. Goals The first objective of this work is to provide a classification of the different kinds of coupling relations, together with the metrics to measure them. The second consists in presenting an overview of the tools proposed until now by the software engineering academic community to extract these metrics. Method This work constitutes a systematic literature review in software engineering. To retrieve the referenced publications, publicly available scientific research databases were used. These sources were queried using keywords inherent to software coupling. We included publications from the period 2002 to 2017 and highly cited earlier publications. A snowballing technique was used to retrieve further related material. Results Four groups of coupling relations were found: structural, dynamic, semantic and logical. A fifth set of coupling relations includes approaches too recent to be considered an independent group and measures developed for specific environments. The investigation also retrieved tools that extract the metrics belonging to each coupling group. Conclusion This study shows the directions followed by the research on software coupling: e.g., developing metrics for specific environments. Concerning the metric tools, three trends have emerged in recent years: use of visualization techniques, extensibility and scalability. Finally, some coupling metrics applications were presented (e.g., code smell detection), indicating possible future research directions. Public preprint [https://doi.org/10.5281/zenodo.2002001]

Geochemical, mineral-petrographic and physical-mechanical characterization of stones and mortars from the Romanesque Saccargia Basilica (Sardinia, Italy) to define their origin and alteration

This paper aims to study the geomaterials of the most important Romanesque-style monument of Sardinia, the Santissima Trinità di Saccargia Basilica (Codrongianos, north Sardinia). The monument was built up on ruins of a pre-existing monastery, and completed in 1116 A.D. Over time, the aspect of the monument is quite changed due to two series of restoration works. The stone materials consist of both grey-black basalts and whitish limestones and marls, intentionally used to give a bichromy effect of the construction. The volcanic rocks belong to the Miocene-Pleistocene volcanic Sardinian activity, while limestones and marls belong to the sedimentary marine Miocene Formation of Meilogu (Logudoro). To define both the origin and the alteration processes of materials, geochemical, petrographic and physical-mechanical investigations of volcanic and sedimentary rocks were carried out on samples collected from monument and possible source outcrops. The integrated chemical (ICP-MS) and petrographic data allowed to ascertain the sourcing sites of raw materials. Moreover, physical-mechanical tests along with X-Ray Diffraction (XRPD) analysis, highlighted the main weathering processes responsible of the chemical-physical alteration affecting the geomaterials, and the newly-formed mineral phases formed on stone surface

Understanding flaky tests: the developer’s perspective

Flaky tests are software tests that exhibit a seemingly random outcome (pass or fail) despite exercising unchanged code. In this work, we examine the perceptions of software developers about the nature, relevance, and challenges of flaky tests. We asked 21 professional developers to classify 200 flaky tests they previously fixed, in terms of the nature and the origin of the flakiness, as well as of the fixing effort. We also examined developers' fixing strategies. Subsequently, we conducted an online survey with 121 developers with a median industrial programming experience of five years. Our research shows that: The flakiness is due to several different causes, four of which have never been reported before, despite being the most costly to fix; flakiness is perceived as significant by the vast majority of developers, regardless of their team's size and project's domain, and it can have effects on resource allocation, scheduling, and the perceived reliability of the test suite; and the challenges developers report to face regard mostly the reproduction of the flaky behavior and the identification of the cause for the flakiness. Public preprint [http://arxiv.org/abs/1907.01466], data and materials [https://doi.org/10.5281/zenodo.3265785]