POSTMAN FOR API TESTING

What Is API Testing 

Testing of API is known as API testing. If the API isn't being tested, it can create significant problems for the client side as they won't receive the desired outputs which they are requesting, and this can lead to severe issues as well as integration and mapping of data is concerned.

Why API Testing Needs To Be Done

Let's look at the various reasons for API testing.

• We have so much relied upon APIs these days. The services that we are receiving result from so many interconnected APIs. If one API goes down or works inappropriately, the whole service will decrease. 
• The internet works over millions of APIs that's need to be tested intensively.
• Sometimes, developers can make buggy APIs which might lead to problems as soon as the application comes live; therefore, it's been highly recommended to validate API.
• Validation of keys is highly required.
• We need to check whether the response is coming is as per boundary value or not.
• Performance testing over API is essential to check whether API works adequately under loads or not.

Types Of API

Following are the different types of APIs.

• SOAP: SOAP is termed as Simple Object Access Protocol. It is a kind of messaging protocol with the help of which a communication is made with HTTP using a soap envelope which contains WSDL, i.e., Web services description language kind of API where the client sends request according to the envelope and server responds according to this XML based architecture. 
• REST: REST stands for REpresentational State Transfer. It's the design pattern of an API. REST architecture contains six constraints: Uniform Interface, Stateless, Cacheable, Client-Server, layered system, Code on Demand. If any API has all these constraints, we can call it a REST API.

Difference Between SOAP and REST 

Postman Tool

Let us understand this with the help of a very day-to-day example of our life.

Everyone knows letters are being sent from one place to another with the help of the post office. A postman delivers our posts from one place to another once they are transferred, and there is a postbox in which we deposit the letters or posts. This technique is similar to this. We are not sending any posts. Instead, we'll send clients' requests to the server via a network. That's why this tool is called Postman.

How To Install Postman

There are two ways to install Postman.

1. Download it from the official website. Here is the URL through which we can download it very quickly as per your requirement.
2. For a temporary purpose, we can add the extension. Following is the URL to add this extension. Once the extension is added, the following is the page that will be seen. Then we need to sign up.

That's how the first screen will appear.

Let's see how it works.

Example

Suppose we have to make a GET request over Postman, and the command is to land on the coding ninja's homepage. Here, we have given the complete URL. After this, we need to click over send, then sent, and download.

Now, we can save our response.

The next step is to select with what application the file needs to be opened.

Here is the desired output.

That's how Postman works.

Working With The Get Request 

GET request means retrieving the information from the URL. After that, no changes can be made at the endpoint. Following are the steps:

1. Set the request field to GET.
2. In the URL field, add the input link.
3. Click on Send.
4.  The "200 OK" message is obtained.
5. Once this is displayed, it will show the successful completion of the request.

This can be confirmed with the help of get requests.

Working With The Post Request

POST requests are entirely different from the GET request. Here, data manipulation will be done at the user's endpoint. Let's understand it step by step.

1. Click on the new tab to create a request.
2. Put the HTTP request to POST.
3. Enter the same link in the request URL.
4. Move to the body tab.
5. In the body, click on raw and select JSON.
6. Copy and paste just one user result from the previous get request.
7. Now click on send.
8. Posted data will be displayed on the body.

Uses Of Postman

Following are the advantages of using Postman.

• Accessibility: Postman tool is straightforward to use. Hence, accessibility is achieved.
• Debugging: Debugging is achieved as Postman helps to check what data is being retrieved.
• Creation of Tests: It tests checkpoints like completing HTTP response status.

FAQs

1. Give common examples of rest API.
   LinkedIn API, Twitter API.
    
2. Why use the postman tool.
   Postman tools offer various advantages like accessibility and efficient responses in a given time frame.
    
3. Why is API necessary?
   API is essential as, with the help of API, we establish links between the two applications. So, without API, it becomes almost impossible to get any service.

Key Takeaways

This blog was all about API testing using Postman. This blog has taught you why the postman tool is used and what API is all about. Also, how necessary it is to test the API. Do read about different types of APIs as these are the most asked questions from an interview perspective. Please upvote if you found this blog worth reading.

Read more blogs to enhance your knowledge over the topic like How do API calls work, REST API, etc.

Recommended Readings:

• Sanity Testing vs Smoke Testing