Modern QA2026Question 2
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1.9Question 2

Prompt: A developer tells you their API does not need an OpenAPI spec because "the code is the documentation." How do you push back, and what testing risks does the absence of a spec create?

What a strong answer should cover:

  • Concrete testing impact: no auto-generated Postman collections, no schema validation, no contract testing
  • Team-wide costs: every new tester has to reverse-engineer the API by reading code or asking developers
  • Drift risk: without a spec, the actual behavior and the intended behavior diverge silently
  • Pragmatic compromise: even a minimal spec is better than none

Example answer:

  • "Without an OpenAPI spec, I cannot auto-generate Postman collections, so every endpoint has to be discovered manually -- which is slow and error-prone."
  • "More importantly, I lose the ability to do schema validation in tests. Instead of validating responses against a contract, I am guessing at what fields should be present. When the developer adds or removes a field, my tests do not catch it unless I manually update expectations."
  • "I would propose a compromise: let me generate a spec from the existing code using a tool like swagger-autogen or FastAPI's built-in spec generation. That gives us a starting point without requiring the developer to write it from scratch."