  Modern code review is a common and essential practice employed in both
industrial and open-source projects to improve software quality, share
knowledge, and ensure conformance with coding standards. During code review,
developers may inspect and discuss various changes including refactoring
activities before merging code changes in the codebase. To date, code review
has been extensively studied to explore its general challenges, best practices
and outcomes, and socio-technical aspects. However, little is known about how
refactoring activities are being reviewed, perceived, and practiced. This study
aims to reveal insights into how reviewers develop a decision about accepting
or rejecting a submitted refactoring request, and what makes such review
challenging. We present an industrial case study with 24 professional
developers at Xerox. Particularly, we study the motivations, documentation
practices, challenges, verification, and implications of refactoring activities
during code review. Our study delivers several important findings. Our results
report the lack of a proper procedure to follow by developers when documenting
their refactorings for review. Our survey with reviewers has also revealed
several difficulties related to understanding the refactoring intent and
implications on the functional and non-functional aspects of the software. In
light of our findings, we recommended a procedure to properly document
refactoring activities, as part of our survey feedback.
