Vassilis E. Zafeiris

Katerina Paltoglou, Vassilis E. Zafeiris

We propose a method that employs static and dynamic analysis for augmenting a test suite with automatically generated unit tests. The method is most suitable for test suites where the stratification of unit, integration and system tests does not conform to the recommended test pyramid structure: numerous unit tests providing high code coverage and forming the base, fewer integration tests in the middle that verify component collaboration, and far fewer system or UI tests at the top that exercise acceptance or other scenarios of use. Instead, integration and system tests represent the majority of test cases, resulting in coarse-grained tests with limited fault localization and longer execution times. The method leverages integration tests, exercising a component and its dependencies, to generate unit tests that verify component dependencies in isolation. We showcase and empirically evaluate the proposed method in the Node.js platform, although it can be ported and adapted to other languages and platforms. The evaluation is based on a research prototype implemented as a Node.js tool and is conducted in the context of twelve open source JS applications (benchmark projects). Evaluation results support the effectiveness and practicality of our approach.

Katerina Paltoglou, Vassilis E. Zafeiris, N. A. Diamantidis et al.

The JavaScript language did not specify, until ECMAScript 6 (ES6), native features for streamlining encapsulation and modularity. Developer community filled the gap with a proliferation of design patterns and module formats, with impact on code reusability, portability and complexity of build configurations. This work studies the automated refactoring of legacy ES5 code to ES6 modules with fine-grained reuse of module contents through the named import/export language constructs. The focus is on reducing the coupling of refactored modules through destructuring exported module objects to fine-grained module features and enhancing module dependencies by leveraging the ES6 syntax. We employ static analysis to construct a model of a JavaScript project, the Module Dependence Graph (MDG), that represents modules and their dependencies. On the basis of MDG we specify the refactoring procedure for module migration to ES6. A prototype implementation has been empirically evaluated on 19 open source projects. Results highlight the relevance of the refactoring with a developer intent for fine-grained reuse. The analysis of refactored code shows an increase in the number of reusable elements per project and reduction in the coupling of refactored modules. The soundness of the refactoring is empirically validated through code inspection and execution of projects' test suites.