API test cases Positive, Negative & functiona/workflow

We are working on the sunbird platform Sunbird.org. We are planning to move our existing documentation (redoc) & api test-cases(written in specific technology) to Postman. So that any adopters of Sunbird platform can view api’s list, documentation & test-cases at one place.

As part of this exercise, we tried for one of our microservice DIAL

Sunbird DIAL api’s

Can you please suggest what is the better way of organizing the test-cases for all positive, negative & workflow scenarios?

Any public sample postman collection for reference would be grateful.