Introduction To API Testing

What is API?

API means Application Programming Interface. API is written by the programmer which enables the communication or we can say it enables the data exchange between two systems. It can be written in any programming language like Java, Python, NodeJS etc. API contains some functions and methods which can be executed by another system.

What is API Testing?

API Testing is different from GUI Testing, it comes under the Business Layer and mainly concentrates over the business logic. This testing doesn't concentrate over the looks and feels of the application. Instead of sending the inputs from the keyboard, in API testing, we use software to call the API and get the output. The output of any API Testing can be in any form it can be in XML format or in JSON format. API Testing can be done by using two type 

1. It can be driven by using any API Testing Tool. 

2. It can be tested by using write your own code.

There are several methods through which we can call our API by simply hitting the API and by simply sending some data. Some methods are 

1. Get Method

2. Post Method

3. Put Method

4. Patch Method

5. Delete Method etc.

Here I am giving you a real life API Testing example through which using POSTMAN tool I am testing my login API using GET and POST Method 

Get method In this method we have to just hit the API using any tool and we have to check and validate our Respond data  

Post method In this method you need to send the data in a particular format through which your application is communicating, it can be JSON format. Here I am giving you some example 

Suppose I have to test my login API in which I have to send the data in JSON format. So using Postman you just have to write your API path and select the Post method to send the data 

API:- and Using POST method you need to send the data in below format and click on send button 

http://50.25.93.123:90/skulocity/api/login/v1

{

"username": "admin"

"password" :"admin@123"

}

Response in JSON

{
    "message": "",
    "timestamp": 1506331715673,
    "extendedMessage": null,
    "error": false,
    "status": "ACCEPTED",
    "data": {
        "authenticationToken": {
          }

Please see the below image which gives you more clear view about this 

THANKS