Toward refactoring evaluation with code naturalness.

Refactoring evaluation is a challenging research topic because right and wrong of refactoring depend on various aspects of development context such as developers' skills, development cost, deadline and so on. Many techniques have been proposed to evaluate refactoring objectively. However, those techniques do not consider individual contexts of software development. Currently, the authors are trying to evaluate refactoring automatically and objectively with considering development contexts. In this paper, we propose to evaluate refactoring with code naturalness. Our technique is based on a hypothesis: if a given refactoring raises the naturalness of existing code, the refactoring is beneficial. In this paper, we also report our pilot study on open source software.