← Walmart Labs Interview Insights

Walmart Labs·Software Engineer·Onsite - Coding / Algorithms·Senior

Senior
May 2026

Summary

Walmart Labs frontend debugging round where you get a broken codebase, a bunch of open tabs, and an AI assistant to help you figure out what's on fire. The whole thing is about actually using the AI tool well, not just brute-forcing fixes yourself.

Questions Asked (1)

Q1

You are given a broken frontend code package and access to an AI coding assistant. Find the failing tests, diagnose the errors, fix the source code so tests pass, and show that you can use the AI tool effectively without just blindly trusting its output.

Root Cause AnalysisTechnical Trade-offsAPI & Integrations
Author's notes

This is less a question and more a whole exercise.

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AI HintsAI Generated

Suggested Approach

Start by running the test suite to identify failures, then systematically diagnose each error by reading stack traces and test expectations. Use the AI assistant to suggest fixes, but critically evaluate each suggestion against your own understanding and the test requirements. Finally, apply verified fixes and re-run tests to confirm resolution.

Pro tip: Treat the AI as a junior pair programmer: ask it to explain its reasoning and generate alternative solutions, then validate with tests and your own code review. This demonstrates both effective tool use and engineering judgment.

1. Run tests and capture failures

Execute the test suite to see which tests fail, and collect error messages, stack traces, and expected vs. actual outputs.

2. Diagnose root causes

For each failure, trace the error to the source code, identify the underlying bug (e.g., logic error, API misuse, missing dependency), and note any patterns.

3. Engage AI assistant with context

Provide the AI with the failing test, relevant source code, and error messages; ask for potential fixes and explanations, but do not apply blindly.

4. Critically evaluate AI suggestions

Review each suggestion for correctness, side effects, and alignment with best practices; test hypotheses in isolation and consider alternative approaches.

5. Apply fixes and verify

Implement the validated fixes, re-run tests to ensure they pass, and check for regressions or unintended consequences.

Key Points to Mention

  • Systematic debugging: using stack traces, console logs, and test expectations to pinpoint issues.
  • AI as a tool, not an oracle: verifying suggestions with tests and code review.
  • Root cause analysis: fixing the underlying problem, not just symptoms.
  • Technical trade-offs: choosing between quick fixes and robust solutions.
  • API & integrations: ensuring correct usage of external libraries or services.
  • Communication: explaining the debugging process and rationale for fixes clearly.

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