  Code review is a mature practice for software quality assurance in software
development with which reviewers check the code that has been committed by
developers, and verify the quality of code. During the code review discussions,
reviewers and developers might use code snippets to provide necessary
information (e.g., suggestions or explanations). However, little is known about
the intentions and impacts of code snippets in code reviews. To this end, we
conducted a preliminary study to investigate the nature of code snippets and
their purposes in code reviews. We manually collected and checked 10,790 review
comments from the Nova and Neutron projects of the OpenStack community, and
finally obtained 626 review comments that contain code snippets for further
analysis. The results show that: (1) code snippets are not prevalently used in
code reviews, and most of the code snippets are provided by reviewers. (2) We
identified two high-level purposes of code snippets provided by reviewers
(i.e., Suggestion and Citation) with six detailed purposes, among which,
Improving Code Implementation is the most common purpose. (3) For the code
snippets in code reviews with the aim of suggestion, around 68.1% was accepted
by developers. The results highlight promising research directions on using
code snippets in code reviews.
