Schemathesis vs Postman: Generating Tests From a Schema or Writing Them From Requests

The article argues that Schemathesis and Postman are not interchangeable, since they solve different problems. Schemathesis reads an OpenAPI, GraphQL, or gRPC schema and generates requests at run time, checking responses against what the schema promises. Postman instead stores requests in collections, which can be scaffolded from an imported spec, and relies on the user to write the assertion scripts. The author notes that Schemathesis works best for uncovering unexpected bugs, running against a live server, and handling multi-step workflows in pytest. The piece is written by the author of apitestgen, a tool that generates test files from a spec, and this is disclosed upfront.