best way to test an api code example

Example 1: 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.

Example 2: what need to verify in api testing

We will verify the accuracy of the data
Will see the HTTP status code
We will see the response time
Error codes in case API returns any error
Authorization would be check
Non-Functional testing such as 
performance testing, security testing.