how to testing web api using testing code example

Example 1: 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.)

Example 2: how to test rest api

First, I verify if each REST API end-point is working as
expected.
- I use POSTMAN for manual API testing and use
RESTASSURED library in Java for automation.
- I send GET, POST, PUT, DELETE type of requests and
verify response status code and response body.
- I also do positive/negative testing of API.


When I do positive testing,
I send
valid request parameters,
valid headers,
valid request json body to valid url and verify that
response status code is 200 and
Json response body data is as expected.
When I do negative testing,

I send
invalid request parameters,
or invalid headers,
or invalid request json body and verify
response status code is not 200.

and Json response body contains error message. (for example, there are 100
employees numbered from 1 to 100, I send 101 as an end-point and I should be
able see 404 Not Found. The requested resource was not found.