All code review should be done in the context of a pull request (PR). Feedback on the changes should be provided as comments on the pull request, especially as inline comments for the specific lines that need to be addressed. When feedback is added, the PR should be assigned back to the engineer to fix. In some cases the code reviewer could fix minor issues themselves. However, it is the responsibility of the original engineer to only assign a pull request for code review once they are confident that it is in a state where it can be merged. The engineer should not rely on the code reviewer to harden and fix up issues that they know are present in the code. Also, if Travis CI reports failures on the pull request, it cannot be assigned for code review.