API Testing

What is API ?

Application programing Interface is basically know as API. API is independent set of code lets say set of functions or procedure, which can be accessible using API request methods. API is useful for cloud base application development where mobile App, web application, desktop app and other services directly access data upon HTTP protocol for data transfer.

Unlike SOAP-based web services, there is no “official” standard for RESTful web APIs. This is because REST is an architectural style, while SOAP is a protocol. Even though REST is not a standard per se, most RESTful implementations make use of standards such as HTTP, URI, JSON, and XML.


Why API need to Test ?

To make sure API returns expected response on giving actual request data
Ensuring that update data structure based on some authentication
Generating more value added parameter combinations to verify the calls with two or more parameters.
Ensure API not gets fail on boundary value conditions
Ensure all functional area work as per expectation based on authentication and no security gap between.
Verifying the Sequence of API calls and check if the API’s produce useful results from successive calls.



Challenges of API testing includes:

Main challenges in API testing is Parameter Combination, Parameter Selection, and Call Sequencing
There is no GUI available to test the application which makes difficult to give input values
Validating and Verifying the output in different system is little difficult for testers
Parameters selection and categorization required to be known to the testers
Exception handling function needs to be tested
Coding knowledge is necessary for testers

API Testing Tools

SoupUI
POSTMAN
Jmeter

Check for REST API response code list.