Code Review

What is code review and why should I do it?

The point of code review is to improve code quality. By drawing on the expertise of reviewers in addition to code authors, code quality can be enhanced and both authors and reviewers will improve their coding skills. Automated testing is a subset of procedures undertaken in a code review, but the most thorough review and feedback comes from other people.

If code review is done correctly, it saves author time. Other developers who review your code must understand why the change has been made and how it works, so if a bug is detected they are able to debug and/or fix it. Reviewing code before it is merged upstream increases the chances that bugs are caught before propogating to the main branch. Reviews should be done often on small chunks of code, therefore each review should not take a substantial amount of time.

Code review checklist

Mozilla science has an excellent checklist for scientific code review. Here are some additional suggestions.

Intrinsic issues

• Argument handling - are there too many arguments, or conversely are global variables assumed? Could redundant argument passing be simplified? Should we be dragging along objects with inputs and outputs. Input arguments and initializing to null?
• Function location, structure, and size
• Efficiency - reducing duplication and using mapping if possible
• Consistent and meaningful name standards
• Documentation
• Error handling - are inputs checked?
• Are unit tests performed?

Extrinsic issues

• Is there functionality in the new code that is duplicated elsewhere in the package?
• Does the new code follow the project standard?
• Are the user guides/tutorials updated?