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Shopify·Software Engineer·Onsite - Coding / Algorithms·Senior

Senior
May 2026

Summary

Pair-programming round at Shopify where I built a rover simulator with an AI coding assistant, then got asked to critique my own output. Uncomfortable but probably the most useful interview format I've been through.

Questions Asked (1)

Q1

You used an AI assistant to write this code and it passes the basic cases. Walk me through what you'd actually fix before shipping it.

Technical Trade-offsSystem DesignAPI & Integrations
Author's notes

This one stung a little because I'd been feeling pretty good about the code working.

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AI HintsAI Generated

Suggested Approach

Acknowledge that AI-generated code is a starting point, not a finished product. Walk through a systematic review process covering correctness, edge cases, security, performance, and maintainability, and emphasize that you would never ship code you don't fully understand.

Pro tip: Frame your answer around risk mitigation: prioritize fixes by impact (e.g., security > correctness > performance > style) and mention that you'd add tests to lock in behavior before refactoring.

1. Understand and Validate the Code

Read through the code line by line to ensure you understand what it does and why. Run it against additional test cases, including edge cases and invalid inputs, to uncover hidden bugs.

2. Check for Security and Data Integrity Issues

Look for common vulnerabilities such as injection flaws, improper input validation, and insecure data handling. Ensure sensitive data is protected and access controls are in place.

3. Assess Performance and Scalability

Analyze time and space complexity, and identify potential bottlenecks. Consider how the code behaves under load and whether it meets the system's performance requirements.

4. Improve Readability and Maintainability

Refactor for clarity, consistent naming, and modularity. Add comments where necessary and ensure the code adheres to team style guides and best practices.

5. Add Tests and Documentation

Write unit, integration, and edge-case tests to verify correctness and prevent regressions. Update or create documentation to explain the code's purpose and usage.

Key Points to Mention

  • AI-generated code may lack proper error handling and edge-case coverage.
  • Security vulnerabilities like SQL injection or XSS are common in AI-generated code.
  • Performance implications: inefficient algorithms or unnecessary database queries.
  • Code maintainability: unclear variable names, lack of comments, and inconsistent style.
  • Importance of writing tests to validate behavior and catch regressions.
  • Need to align with team conventions and integrate with existing systems.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.