Google Engineering Manager Code Review Interview

The code review interview is part of the onsite round for Google’s Engineering Manager (EM) role, and yes—it’s technical. Google’s a super engineering-driven company (arguably the most technical of the FAANG group), so even if you’re applying for a management role, expect to be tested on your coding skills. You typically get the choice between a coding interview where you have to actually code to find a solution, or a coding review. Either way, you'll want to make sure your knowledge of common data structures and algorithms is refreshed and up-to-date. 

In the code review, you’ll be presented with a problematic piece of code—a snippet, function, or file from Google’s domain—and asked to evaluate what’s wrong with it. This simulates real-world code review, requiring you to spot bugs, performance issues, or design flaws and suggest improvements. You’re basically stepping into the shoes of a senior tech lead here, where you’re not just finding errors but looking at code design, readability, and potential improvements.

The whole thing lasts around 45 minutes, so keep your explanations concise but detailed. The best approach is to comment on the code to highlight areas for improvement and add context to your suggestions, unless your interviewer specifically requests direct modifications..

Your goal is to simulate how you would conduct a code review in real life while keeping in mind the time constraints. Here’s a 5-point checklist to nail your code review session:

1. Start by Scanning for Bugs and Defects

Your first priority is to spot errors and defects, no matter how minor, to ensure the code functions as intended. Perform a line-by-line review and identify potential issues such as:

• Inconsistent and non-descriptive naming
• Unclear code segments without explanations
• Disorganized and poorly formatted structure

You should also check for boundary conditions - improve the time complexity of the algorithm, add nullable and nonnull annotations, inspect method/variable declarations, etc.

Make sure you walk through the code methodically and write comments as you decipher the algorithm. This helps to showcase your understanding and provides a clear trail for the interviewer to follow. 

If you’re a bit rusty (e.g., you haven’t been hands-on with coding for a while), be upfront with your interviewers. However, make sure to brush up on key concepts like recursion, DFS, and BFS algorithms before the interview—that’s typically enough to get through this round.

2. Be Ready for Edge Cases and Hypotheticals

Expect the review to move into open discussion. You may be asked questions like, "What would happen in this edge case?" or "How would you break this code, or prevent it from breaking?" Google might even turn this into a role-play scenario, with the interviewer acting as the engineer whose code you're reviewing. In such cases, the interviewer may push back on your suggestions and expect you to walk them through your reasoning.

3. Match Google’s Code Culture

Code reviews are also an opportunity for Google to assess how well you fit into their “code culture.” Ask yourself:

• Can anyone read your code and easily understand it?
• Can your code run out of the box without modifications?
• Is your code well-organized? Did you write tests?

Remember, it’s not just about the quality of your code but also your ability to accept and implement feedback. Can you take suggestions and build upon them? Can you recognize what to optimize, and more importantly, what not to over-optimize? Your reactions are crucial here: How do you handle feedback when a colleague points out errors in your code? How do you react when you don’t know something? Be mindful of these aspects.

4. Show off your coding know-how

Fourth tip and a piece of good news — code reviews are your chance to show off. Typically, you'll be reviewing code that wasn’t written during the interview, so you’re in a non-threatening environment where you can demonstrate how you approach coding. Offering constructive feedback on existing code is often more valuable than solving a random coding problem with an optimal solution.

Make sure to write comments for all functions, explaining what they do. Look for minor errors, and review the overall correctness of the code—does it work as intended? Also, think about test cases—are there any test cases that should be added or improved? You don’t need to write them out, but mentioning them shows your attention to detail.

5. Talk your thought process through

The final tip is to talk through your thought process as you review the code. Don’t just silently add comments—explain your reasoning in a clear and straightforward manner. Imagine you’re walking a junior engineer through your review in a respectful, non-condescending way. This shows your ability to communicate technical concepts effectively.

Focus on providing constructive, specific, and actionable feedback. Avoid getting bogged down by minor stylistic issues that don’t affect the code’s functionality. Also, don’t just look for errors—if the code is well-written, make sure to highlight that too. Offering positive feedback shows your ability to recognize quality code and will help you score points for "Googleyness." It also signals that you know how to balance critique with appreciation.

1. Practice with Open-Source Projects

In addition to brushing up on your code reviewing skills, make sure you’re also writing code regularly. This way, you’ll get hands-on experience reviewing code in real-world scenarios, while also improving your coding ability.

1. Practice with an Expert

Practicing on your own is helpful, but there’s only so much you can do without feedback. That’s why we recommend mock code review interviews with former interviewers from Google or other top tech companies. This will give you insight into how experts approach reviews and help you refine your skills. 

Once you feel ready for some practice, or just want a sense-check of your preparation level, you can book an anonymous mock interview with a Google EM on Prepfully.