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Early-stage Startup·Software Engineer·Online Assessment (OA)·Intermediate

Intermediate
May 2026Remote

Summary

Coding assessment on Coderbyte for a software engineer role, working with provided skeleton code for a permit-checking system. The problem itself wasn't too bad once I understood what was being asked, but I didn't fully get the requirements until I started writing test cases, which felt a bit backwards.

Questions Asked (1)

Q1

You're given a permit-checking system that currently returns 'NotRequired' when no permit condition matches. Modify it to distinguish between three states: Required, NotRequired, and Unknown, so the system can tell the difference between 'we know a permit isn't needed' versus 'we haven't looked into this yet'.

System DesignTechnical Trade-offsAdaptability & Ambiguity
Author's notes

The ambiguity in the original return value is actually a pretty real-world problem and I appreciated that framing.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the current system's behavior and the desired three-state outcome, then propose a design that introduces an explicit 'Unknown' state without breaking existing consumers. Discuss how to represent and propagate this state, and outline a migration strategy that balances correctness with backward compatibility.

Pro tip: In an early-stage startup, favor a simple, incremental change over a big rewrite—show you can ship value quickly while keeping the door open for future refinement. Also, explicitly call out how you'd handle existing callers that assume a binary outcome, as this demonstrates production empathy.

1. Clarify Requirements and Current Behavior

Ask questions to understand the current permit-checking logic, its callers, and what 'Unknown' means in the business context. Confirm whether the three states are mutually exclusive and how they should be surfaced to users or downstream systems.

2. Design the State Representation

Propose a clear representation for the three states, such as an enum or a result object with a status field. Consider using an explicit 'Unknown' value rather than null or a default, to avoid ambiguity.

3. Modify the Logic to Distinguish States

Update the permit-checking algorithm to return 'Unknown' when no condition matches but the system hasn't definitively determined that no permit is required. This may involve tracking whether all relevant checks have been performed.

4. Handle Backward Compatibility and Migration

Plan how to update existing callers that expect a binary result. Options include a compatibility layer, feature flags, or a phased rollout, ensuring no disruption to current functionality.

5. Test and Validate the New Behavior

Outline test cases for all three states, including edge cases where the system might incorrectly return 'Unknown'. Discuss monitoring and logging to track the new state in production.

Key Points to Mention

  • Use an enum or sealed class to represent the three states explicitly, avoiding boolean or null-based approaches.
  • Consider the impact on existing API contracts and consumers; propose a migration path such as versioning or adapters.
  • Define clear criteria for when 'Unknown' is returned—e.g., missing data, incomplete checks, or unhandled conditions.
  • Discuss how to propagate the new state through the system, including logging, metrics, and user-facing messages.
  • Emphasize incremental delivery: start with a minimal change that adds 'Unknown' and iterate based on feedback.
  • Mention the importance of testing all state transitions and ensuring idempotency in permit checks.

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