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
https://documenter.getpostman.com/view/4214340/UVsMv6Kd

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

Any publich sample postman collection for reference would be greatefull.