How to test API if application state changes?

Question

API

I want to learn how to test API, but I don't understand how to do it.

To test something, you need a server on which the application is deployed. At the moment the request is sent, the state of the server will change and during the next test run the same request will fail.

Those. I'm not interested in how to write the tests themselves (using postman or something else), but how to deal with the state of the application.

Tell me, please, where to dig?

Answer 1

You will have to test both the server and the client at once, rolling back the server state before starting the test and in the process to a certain starting / required for the corresponding test.
If this is not your server, then I sympathize. Will have to test with this feature in mind. In addition, normal systems offer test servers so that, for example, if a test requires, for example, money on a deposit (testing financial services, but just purchases)