Code Review Automation can reduce human efforts during code review by automatically providing valuable information to reviewers.
Nevertheless, it is a challenge to automate the process for large-scale companies, such as Samsung Electronics, due to their complexity: various development environments, frequent review requests, huge size of software, and diverse process among the teams.

In this work, we show how we automated the code review process for those intricate environments, and share some lessons learned during two years of operation. Our unified code review automation system, Code Review Bot, is designed to process review requests holistically regardless of such environments, and checks various quality-assurance items such as potential defects in the code, coding style, test coverage, and open source license violations.

Some key findings include: 1) about 60% of issues found by Code Review Bot were reviewed and fixed in advance of product releases, 2) more than 70% of developers gave positive feedback about the system, 3) developers rapidly and actively responded to reviews, and 4) the automation did not much affect the amount or the frequency of human code reviews compared to the internal policy to encourage code review activities.
Our findings provide practical evidence that automating code review helps assure software quality.