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How to test a REST API?

REST API testing is one of the basic procedures involved in backend testing. It requires the use of the right tools (several basic, free software are available) and knowledge of how to integrate the interface into the architecture. Those who plan to develop a career in the direction of software testing should definitely pay some attention to learning about REST API testing, as it is an important skill in terms of deepening their competence and building an image of a valuable employee.

REST API testing – let’s start with the basics

Both a beginning tester of mobile applications and tester of web applications may encounter the name REST API. Before we get into the details of the procedures and why you should perform them, let’s consider what REST API basically is. The name has two parts:

  • REST – or Representational State Transfer, is a system architecture developed for accessing resources via the HTTP protocol.
  • API – or Application Programming Interface, which is a set of ways for a user to communicate with a system (interface).

Testing REST APIs allow you to work with HTTP requests without a graphical interface. Therefore, it is a solution that can allow you to significantly improve the work on software and perform certain activities at an early stage of the implementation of a given piece of software, when the visual elements have not yet been implemented.

Testing API – the procedure depends on the chosen test software

To test the REST API, use one of the commercially available software developed for this type of operation. Both open-source software and commercial tools are available on the market. Those worth noting are: JMeter, Rest-Assured, Postman, Swagger, or HttpMaster. Depending on the chosen tool, the procedure for testing the REST API looks different. Here we operate on four of the eight methods, namely. GET, PUT, POST and DELETE (from the HTTP protocol). The test configuration caninclude selecting a url, setting conditions, or selecting a header. After the test, we get HTTP statuses (response codes), which are expressed by codes (e.g., 200 – the success of the request, 403 – no access to the request, 302 – redirection of the request). The test report is most often a standard JSON file.

Do I need a development background for REST API testing?

As a rule, carrying out the REST API testing procedure does not require special programming knowledge. The right tools will guide us through the relevant procedures quite quickly. What is important, however, is the proper selection of the testing program for the program to be tested. It is important to know in what language the object of our tests was written. For example, if we are talking about a JavaScript creation, it seems a good idea to use Postman. Software development facilities in REST API testing can favor the implementation of automation. Performing tests without having to enter data each time allows you to test more requests in less time. A software tester who deals with REST APIs does not need to have an established knowledge of programming in a particular language, although a basic knowledge of Python, for example, may come in handy.