sending invalid endpoint is valid test case for api testing? code example

Example 1: if endpoint is not ready how would use test it

I would mock it with Postman
and swap the base url when it's ready

Example 2: how do you do positive api testing

How I do positive testing in api, 
	- I send valid path and query parameters, 
	- valid headers, 
	- valid request body to valid url and verify that 
	- response status code is correct and 
	- response body is as expected
    
How I do negative testing in api,
	- I send invalid request parameters
	- or invalid headers
	- or invalid request json body and verify 
    that response status code is not 200 
	- and response body contains error message 
    (for example there are 100 employees numbered
    from 1 to 100 I send 101 as a parameter and I
    should be able see 404 Not Found 
    The requested resource was not found.)