Dev
API Test Case Generator
Testing only the happy path leaves a large class of bugs untested — the ones that appear when authentication is missing, a constraint is violated, or a client sends DELETE to an already-deleted resource. This generator produces a method-tailored test checklist. One input controls the output: the HTTP method — GET, POST, PUT, or DELETE. For each method, four method-specific cases and five cross-cutting ones are returned. GET covers response shape, pagination, filtering, and empty results. POST covers 201 creation, 422 for missing fields, 409 for duplicates, and extra-field handling. PUT covers full updates, stale-data 409, validation, and idempotency. DELETE covers 204, idempotency, cascade behaviour, and authorization. Cross-cutting — 401, 403, 404, and 429 — appear for every method. Translate each line into an assertion in your test framework and add domain-specific cases on top.
How to use
- Choose your options above
- Click Generate
- Copy your result
Detailed instructions
- Pick the HTTP method of the endpoint.
- Click Generate to see the test checklist.
- Turn each line into a test in your framework.
- Add cases for your specific business rules.
Use Cases
- •Planning a test suite for a new endpoint
- •Reviewing whether a pull request covers edge cases
- •Remembering the negative cases that bugs hide in
- •Onboarding QA to an API testing standard
- •Building a regression checklist before a release
Tips
- →Write the negative cases first — they catch the most bugs.
- →Assert the response body shape, not only the status code.
- →Test pagination at the boundaries, not just the middle.
- →Keep the checklist in your repo as living documentation.
FAQ
what cases does the generator produce for each method
Four method-specific cases plus five cross-cutting ones. GET gets response shape, pagination, filtering, and empty results. POST gets 201 creation, 422 for missing fields, 409 for duplicates, and extra-field handling. PUT gets full update, stale-data 409, full validation, and idempotency. DELETE gets 204, idempotency, cascade behaviour, and authorization. Every method also gets 401, 403, 404, and 429.
does the generator write test code
No — it produces a checklist of scenario descriptions. Translate each into an assertion in your test framework. The checklist is framework-agnostic and useful in any language or test runner.
why so many negative cases
Happy-path tests rarely catch the bugs that appear in production. Authentication gaps, constraint violations, and unexpected input are where real failures live. The checklist leans into these deliberately so coverage goes beyond the path your code was written for.
are these all the tests I need
No — they are a strong baseline for common API behaviour. Add cases for your specific domain rules, side effects, and integration points on top. Use the checklist as a floor, not a ceiling.
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