Code reviews are a vital part of the software development lifecycle. By thoroughly reviewing each other’s code changes before merging them into the main codebase, development teams can catch bugs early, improve code quality, and spread knowledge across team members. However, not all code review practices actually lead to great outcomes. In this comprehensive guide, we’ll explore the most effective techniques and best practices you can follow to get the most out of your code reviews. Based on recommendations from industry experts and leaders, we’ll provide actionable and proven tips to make your code reviews higher quality and more beneficial for your team.

Establish a Strong Code Review Culture  

The foundation of impactful code reviews is instituting them as an integral part of your team’s culture and processes. Set the expectation that peer code reviews are required before any code gets merged.

Set Clear Goals for Each Code Review

For each code review, establish clear objectives upfront. Is the focus finding bugs? Ensuring adherence to coding standards? Evaluating performance optimizations? Defining specific goals helps reviewers know what to concentrate on and streamlines the process. 

For example, you may want to focus a review on catching potential security vulnerabilities if the code modifies sensitive user data. Or you may want to focus on style and readability standards for an API that will be shared across teams. Setting objectives aligns expectations.

Keep Reviews Focused and Scoped

Try to keep code reviews focused by only including small chunks of code changes at a time. Avoid massive 1000+ line pull requests that touch dozens of files. These large reviews can overwhelm reviewers, leading to overlooking issues. 

As a rule of thumb, target reviewing 400 lines of code or fewer for optimal results. Reviewing small and focused code blocks improves the quality of the inspection.

Example of a focused code review

• // Changes:
• // 1. Added input validation 
• // 2. Fixed bug throwing 500 error 
• // 3. Improved logging for debugging

function createUser(name, email) {

  // Added validation
  if (!name || !email) {
    throw new Error('Name and email are required');
  }

  // Bug fix
  const user = User.create({ name, email });

  // Logging
  console.log('Created new user successfully', user);
  
  return user;
}

Conduct Reviews in a Collaborative Manner 

Maintain a Respectful and Constructive Tone

Always provide code review feedback in a way that is professional, respectful, and geared towards learning. The tone you use in a review goes a long way. Pose any critiques as suggestions rather than commands.

For example, you could frame a comment as: “Have you considered initializing this variable here instead for better readability?” Rather than: “Move this variable initialization.”

Discuss Face-to-Face When Needed

For particularly complex code changes or solutions, schedule face-to-face discussions with the author. This real-time communication eliminates any ambiguities in the review comments and provides a space for the author to explain their approach more thoroughly.

Follow Best Practices for High-Quality Reviews

Leverage Checklists for Consistent Reviews

Create a code review checklist that all reviewers follow. This checklist should act as a list of requirements that each pull request must satisfy before approval. Using a standardized checklist ensures nothing gets missed.

Some common checklist items:

• Follows style guide conventions
• Meaningful commit history
• Adequate test coverage included
• No sensitive credentials/keys
• Code is commented for clarity
• Code is documented where applicable

Automate What You Can

Any manual checks and validations that can be automated should be. Leverage tools like linters to programmatically check for style violations. Execute unit and integration test suites as part of reviews. Use code quality and security tools to analyze code for vulnerabilities. Automating these types of checks leaves the human reviewers free to focus on deeper logic inspection.

Review Code in an IDE

Rather than just using GitHub/GitLab’s web UI, reviewers should clone the branch and inspect the code in their IDE. Using an IDE provides better navigation and contextual understanding of code changes. Modern IDEs also have many code inspection features built-in.

Keep Pull Requests Small

As mentioned earlier, keeping pull requests focused and small is key to an efficient review process. High-level guides recommend pull requests be limited to 300-500 lines of code. The smaller the pull request, the easier it is to thoroughly review all changes included.

Conclusion

Implementing practices like establishing clear goals, maintaining a constructive tone, leveraging checklists, and keeping changes scoped sets your team up for impactful code reviews. By following these and other best practices consistently, you’ll notice tangible improvements in code quality, team collaboration, and development velocity over time. The small time investment required to hone your code review process pays massive dividends. Use these proven recommendations to make your good code reviews great!