How Effective Code Reviews Boost Quality and Team Skills

Goal

Control code style and design requirements through systematic code reviews. Studies show code reviews can detect 30%–70% of deep logical and coding errors, significantly improving software quality and helping developers raise their technical level.

Principles

Conduct reviews via Merge Requests (MR).

Start reviews early; early reviews serve as design reviews.

Provide review feedback within three working days.

Keep each MR focused on a single tightly‑related task.

Limit a review to 200–400 lines of code.

The code under review must have tests.

Incorporate review findings into development standards and automate checks where possible.

Review Focus

Testing

Is the code testable? Avoid hidden dependencies and ensure test frameworks can be used.

Are tests understandable?

Do tests cover correct paths, exception cases, and other relevant scenarios?

Is test coverage not decreasing?

Do unit tests verify the intended functionality?

Are array out‑of‑bounds checks present?

General Items

Does the code work and meet functional expectations?

Is the code modular?

Are there replaceable global variables?

Is there any commented‑out code?

Are loops bounded with proper termination conditions?

Can any code be replaced by library functions?

Are unnecessary logs or debug statements removed?

Security

Are all input data validated for type, length, format, and range, and properly encoded?

Are third‑party tool errors captured?

Are output values checked and encoded?

Are invalid parameter values handled safely?

Documentation

Are all functions documented with comments?

Is unconventional behavior and edge‑case handling described?

Are third‑party libraries and functions documented?

Are unfinished code sections marked (e.g., TODO) or removed?

Readability & Maintainability

Do names clearly describe variables, methods, and classes?

Are comments present that explain intent or business rules?

Is the purpose of each method quickly understandable?

Are exception messages clear?

Is the code simple and easy to understand?

Is there duplicate or redundant code?

Recommended Practices

Create an MR to start the review process.

Open the MR as early as possible; for design discussions, create the MR immediately after branching.

Prefix unfinished MRs with WIP: (Work In Progress).

If CI fails, do not waste time reviewing.

Maintain an OWNER list per project to auto‑assign reviewers.

Reviewers should receive automatic notifications and provide feedback within three working days.

Link review issues to specific files or lines for clear communication.

Authors must respond after fixing issues to inform reviewers.

Reviewers change the status of issues.

When all issues are resolved, the reviewer approves the MR and merges the code to the master branch.

Metrics

Number of lines changed per MR.

Average waiting time for MR merge.

Number of MRs merged per day.

Number of review issues per MR file count.