Code Review

 In doing a code review, you should make sure that:

• The code is well-designed.
• The functionality is good for the users of the code.
• Any UI changes are sensible and look good.
• Any parallel programming is done safely.
• The code isn’t more complex than it needs to be.
• The developer isn’t implementing things they might need in the future but don’t know they need now.
• Code has appropriate unit tests.
• Tests are well-designed.
• The developer used clear names for everything.
• Comments are clear and useful, and mostly explain why instead of what.
• Code is appropriately documented (generally in g3doc).
• The code conforms to our style guides.

Source : https://google.github.io/eng-practices/review/reviewer/looking-for.html