What good API testing looks like
API tests run below the user interface, so they are fast and stable. They check status codes, response bodies, headers, pagination, idempotency, error formats and authorization rules for each role. Good suites also cover awkward inputs such as missing fields, oversized payloads, wrong types and duplicate requests, which is where defects tend to hide in practice. We test them at every level.
We derive tests from the OpenAPI or GraphQL schema where one exists, then add scenario tests that chain calls the way real clients do, such as create an order, pay, cancel and verify the refund. Data is created through the API itself and cleaned up afterwards, so runs never depend on a shared database state. We keep each scenario independent so failures point to one cause and suites can run in parallel.
