Understanding API Testing and its Types

api testing

Let us understand API Testing and its Types. API testing is a type of software testing that involves testing APIs directly. But also, as a part of integration testing to check whether the API meets the required expectations. The main focus lies on a Business logic layer of the software architecture. Moreover, API testing can be performed on any software system. However, API testing is entirely different from GUI Testing.

Functional API Testing

While SoapUI includes basic functional, load, and security testing. Moreover, this involves verifying the behaviour of a system matches expected usability and functionality requirements.

Further, an API works on a series of requests and parameters to invoke a response. This data is usually from another system or database. Subsequently, SoapUI works by sending requests and parameters against a system, and then verifying whether the response received is correct.

What to Test by API

Basically, on API Testing, we send a request to the API with the known data and we analyse the response.

Firstly, Data accuracy
Secondly, HTTP status codes
Thirdly, Response time
Fourthly, Error codes in case API return any errors
Subsequently, Authorization checks
Lastly, Non-functional testing such as performance testing, security testing

UI Testing and API Testing

UI (User Interface) testing tests the graphical interface part of the application. Further, Its main focus is to test the look and feel of an application. However, API testing enables the communication between two different software systems. Subsequently, its main focus is in the business layer of the application.

API Testing Types

API testing typically involves the following practices:

First of all, Unit testing: To test the functionality of individual operation
Secondly, Functional testing: To test the functionality of broader scenarios by using a block of unit test results tested together
After this, Load testing: To test the functionality and performance under load
Subsequently, Runtime/Error Detection: To monitor an application to identify problems such as exceptions and resource leaks
In addition, Security testing: To ensure that the implementation of the API is secure from external threats
Moreover, UI testing: It is performed as part of end-to-end integration tests to make sure every aspect of the user interface functions as expected
Lastly, Interoperability and WS Compliance testing: Interoperability and WS Compliance Testing is a type of testing that applies to SOAP APIs.

API Testing Benefits

First of all, API Testing is time effective when compared to GUI Testing. API test automation requires less code so it can provide faster and better test coverage.
Secondly, API Testing helps us to reduce the testing cost. With API Testing we can find minor bugs before the GUI Testing. These minor bugs will become bigger during GUI Testing. So finding those bugs in the API Testing will be cost-effective to the Company.
Further, API Testing is language independent.
Lastly, API Testing is quite helpful in testing Core Functionality. We can test the APIs without a user interface. In GUI Testing, we need to wait until the application is available to test the core functionalities.

API Testing Challenges

First of all, Main challenges in Web API testing is Parameter Combination, Parameter Selection, and Call Sequencing.
Subsequently, there is no GUI available to test the application which makes difficult to give input values.
Further, Validating and Verifying the output in a different system is a little difficult for testers.
Last but not least, Parameters selection and categorization is required to be known to the testers..

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