Section: New Results

Software Quality: Taming Software Evolution

Software metrics do not predict the health of a project. More and more companies would like to mine software data with the goal of assessing the health of their software projects. The hope is that some software metrics could be tracked to predict failure risks or confirm good health. If a factor of success was found, projects failures could be anticipated and early actions could be taken by the organisation to help or to monitor closely the project, allowing one to act in a preventive mode rather than a curative one. We were called by a major IT company to fulfil this goal. We conducted a study to check whether software metrics can be related to project failure. The study was both theoretic with a review of literature on the subject, and practical with mining past projects data and interviews with project managers. We found that metrics used in practice are not reliable to assess project outcome. [22]

How Do Developers React to API Evolution? Software engineering research now considers that no system is an island, but it is part of an ecosystem involving other systems, developers, users, hardware,. .. When one system (e.g., a framework) evolves, its clients often need to adapt. Client developers might need to adapt to functionalities, client systems might need to be adapted to a new API, client users might need to adapt to a new User Interface. The consequences of such changes are yet unclear, what proportion of the ecosystem might be expected to react, how long might it take for a change to diffuse in the ecosystem, do all clients react in the same way? We report on an exploratory study aimed at observing API evolution and its impact on a large-scale software ecosystem, Pharo, which has about 3,600 distinct systems, more than 2,800 contributors, and six years of evolution. We analyze 118 API changes and answer research questions regarding the magnitude, duration, extension, and consistency of such changes in the ecosystem. The results of this study help to characterize the impact of API evolution in large software ecosystems, and provide the basis to better understand how such impact can be alleviated. [27]

Does JavaScript software embrace classes? JavaScript is the de facto programming language for the Web. It is used to implement mail clients, office applications, or IDEs, that can weight hundreds of thousands of lines of code. The language itself is prototype based, but to master the complexity of their application, practitioners commonly rely on some informal class abstractions. This practice has never been the target of empirical investigations in JavaScript. Yet, understanding it would be key to adequately tune programming environments and structure libraries such as they are accessible to programmers. We report a large and in-depth study to understand how class emulation is employed in JavaScript applications. We propose a strategy to statically detect class-based abstractions in the source code of JavaScript systems. We used this strategy in a dataset of 50 popular JavaScript applications available from GitHub. We found systems structured around hundreds of classes, suggesting that JavaScript developers are standing on traditional class-based abstractions to tackle the growing complexity of their systems. [28]