Code review

When Submitting a Pull Request

When you have code ready to be reviewed, and it meets the code guidelines, open a pull request to ask for it to be merged into the codebase.

To help make the review go smoothly, here are some general guidelines:

  • Your pull request should address a single issue.
    • It’s better to split large or complicated PRs into discrete steps if possible. This makes review more manageable and reduces the risk of conflicts with other changes.
  • Give your pull request a brief title, and use the description to provide key information:
    • Provide a list of the key changes
    • If your PR addresses an existing ticket, link to it with “Fixes #123”. This will make it easy to refer back to the original ticket and automatically close it when the PR is merged.
    • If you’ve discussed the issue, or just want to alert someone to your PR, tag them by including their @username.
    • Link to relevant resources, such as Wiki pages, mailing list threads, specifications, or other tickets. This makes it easier to understand the full context of your PR.
  • Please be patient. Your PR may not be reviewed right away, since the people doing code review are often busy, and may be traveling, in a different time zone, or otherwise not available to review your code immediately.
    • Especially if it’s blocking other work, it’s fine to ask someone to review, either by tagging them in a comment or asking on Slack or at the weekly tech call.
  • Respond to code review comments, with discussion where it’s appropriate or by pushing additional commits to the branch. They will be added to the same PR automatically.
  • If another PR is merged and conflicts with your changes, you may need to rebase your PR.

When Reviewing a Pull Request

Pull requests are evaluated in many different ways; fortunately, we have tools to help us with code review so that human review can focus on overall code quality and maintainability. For instance, we use:

  • TravisCI, to ensure the test suite is passing
  • Rubocop, to be consistent w/ a baseline of Ruby style conventions
  • Coveralls, to ensure code changes are covered by test changes
  • Hound, to be consistent w/ Javascript and CSS style conventions
  • CodeClimate, to flag obvious code smells early for remediation

When reviewing a pull request, please take the time to review the changes and get a sense of what is being changed.

The key things to focus on are:

  • Are the PR description and commit messages clear?
  • Do the functional code changes match the PR description?
  • Does the PR contain tests for new features or bugfixes?
    • Not all PRs require tests, such as wording changes or simple refactoring.
  • Does the commit contain more than it should? Are two separate concerns being addressed in one commit?

As a reviewer, it’s also your responsibility to make sure:

  • Does the submitter have a signed CLA on file?
  • Did the Travis tests complete successfully?
  • Is there a significant drop in code coverage?
  • Do all new or changed methods, modules, and classes have comments?

Merging Pull Requests

When merging pull requests:

  • Give discussion time to settle down. When there is a contentious discussion, please allow 24 hours before merging to make sure everyone’s had a chance to respond.
  • It is considered “poor form” to merge your own request, and you should be cautious when merging pull requests from other developers at your own insitution.
  • If you are uncertain, bring other contributors into the conversation by creating a comment that includes their @username.
  • If you like the pull request, but want others to chime in, create a +1 comment and tag a user.