This one took me longer than it should have.
First, clarify the expected behavior when a folder is passed—should it process all files recursively, raise an error, or something else? Then, systematically trace the code path that handles input to identify where file vs. folder distinction is missing, and propose a fix that aligns with the intended behavior while considering edge cases and trade-offs.
Pro tip: Demonstrate proactive debugging by suggesting you'd write a unit test that passes a folder to the function to reproduce the bug, then fix it and verify the test passes. This shows you value test-driven development and root cause analysis.
Ask the interviewer what the expected behavior is when a folder is provided as input—should it process all files, raise an error, or something else? This ensures your fix aligns with the intended use case.
Mentally or verbally trace the code path that handles input, and identify where the distinction between file and folder is missing. Consider writing a quick test to confirm the bug.
Determine why the code doesn't distinguish between file and folder—e.g., missing os.path.isdir check, or assuming input is always a file. Consider potential side effects of the bug.
Suggest a fix that correctly handles both cases, such as checking os.path.isdir and either raising an error or processing files within the folder. Discuss trade-offs of different approaches.
Outline how you would test the fix, including edge cases like empty folders, nested folders, or permission issues. Mention adding a regression test to prevent future occurrences.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
This was the most interesting of the three.
First, identify the missing visit function by examining the template processor's node types and the visitor pattern implementation. Then, implement the visit function for the missing node type to ensure its arguments are written to the output. Finally, verify the fix by testing the template processing with the node type.
Pro tip: Demonstrate a systematic debugging approach: use logging or a debugger to trace the visitor dispatch and confirm the missing function. Also, consider adding a test case to prevent regression.
Review how the template processor uses the visitor pattern to traverse nodes and generate output. Identify the base visitor interface and existing visit functions.
Search for the node type that lacks a corresponding visit function. Check the visitor implementation and compare with other node types.
Write the visit function for the missing node type, ensuring it correctly writes the node's arguments to the output. Follow the pattern of similar visit functions.
Create a test case that exercises the node type and verifies that its arguments are included in the output. Run existing tests to ensure no regressions.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Be honest about whether you attempted the optional bug, and if you did, explain your reasoning and the outcome. If you didn't, justify your decision by prioritizing the required tasks and managing time effectively. Either way, show that you can make thoughtful trade-offs under ambiguity.
Pro tip: Emphasize that you communicated your decision to the interviewer before proceeding, demonstrating respect for their guidance and an understanding of priorities. This shows maturity and good judgment.
State clearly whether you attempted the optional bug or not, and briefly explain why you made that choice.
If you attempted it, describe how you assessed the risk and time investment. If you skipped it, explain how you prioritized the required tasks.
If you attempted it, detail what you did and whether it was successful. If you skipped it, mention any alternative actions you took, like noting it for later.
Mention how you communicated your decision to the interviewer, showing that you value their input and can manage expectations.
Summarize what you learned about balancing thoroughness with time constraints, and how you would approach similar situations in the future.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.