API is the interface that enables the application’s functions to be accessed and used externally or remotely. We can also say that an API is a software tool that allows two applications to communicate with each other. API allows any server to return a response and access the application on the server from different platforms.
One of the API methods that is frequently preferred in software development processes and enables applications to communicate with each other within the framework of certain protocols is Rest API. Since Rest APIs are considered as the doors that the application opens to the outside, Rest APIs can be used by external applications under the conditions allowed by the application. In this case, the need to test the API before it is used by an application has emerged.
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What is API Testing
These are tests to verify API requests, parameters, functionality, perform boundary value analysis, and detect errors. It’s also a good way to measure the performance of pipelined APIs. The return value that comes with APIs is checked against the input condition. API tests provide assurance on usability, functionality, reliability, performance and security.
Importance of API Testing
You need to make sure that the API is working correctly first. The functionality of the API is very important. API tests are of great importance in terms of limit value analysis. The biggest benefit is that it is very important in terms of finding bugs. The purpose of API testing is to improve the code written in order to increase quality and to produce a better product or application.
Benefits of API Testing
- API testing allows us to easily verify the response and data we want.
- User interfaces should be evaluated based on how they are accessed. API tests can be managed in a controlled manner.
- When API tests fail, it is very useful in terms of increasing the quality as errors can be detected in a short time.
What is Postman
Postman is a powerful HTTP client for sharing, testing, developing, documenting and monitoring APIs, enabling users to quickly put together both simple and complex HTTP requests. Postman basically works as a rest client and Chrome extension. It provides a lot of goodies that are extremely successful for API testing and consumption.
For more information about Postman: https://www.postman.com/
How to use Postman
After logging into the Postman application, a screen like the one below welcomes us.
Then, by pressing the “+” button, a new tab opens in Postman and we can write the Rest API we want to test in this tab.
We can write “https://jsonplaceholder.typicode.com/todos” test Rest API in the “Enter request URL” field and then press the Send button on the right.
As seen in the picture above, Postman gives us a lot of information such as data in Rest API, HTTP Status Code, response time.
While there are many ways to test APIs, doing it with an API Testing Tool is always a time-saver. Although Postman is one of the most popular tools in this field, there are many automation tools used for API Testing. Among them; They include Jmeter, Postman, SoapUI, Katalon Studio, Tricentis Tosca, Rest Assured, Karate DSL, Apigee and Assertible.