How do you validate JSON schema in API tests?
- JSON schema
- validation
- response verification
Answer it first, then compare. Nothing here is saved or scored.
Model answer
Use JSON Schema validation libraries (Ajv for JavaScript, jsonschema for Python) to verify response structure: required fields present, correct data types, string formats (email, date-time, UUID), enum values, and array item types. Store schemas as files and validate every API response against them. This catches breaking changes early, a removed field or type change fails the schema check even if the endpoint returns 200.
What interviewers listen for
- Schema-first thinkingYou validate response shape before you assert on values, every time.
- Status-code literacyYou can defend why 401 vs 403 vs 422 matters for the consumer.
- Contract awarenessYou know when consumer-driven contract tests beat end-to-end checks.
- Auth fluencyYou can describe rotating tokens across parallel workers without secrets in logs.