What Is API Testing? | Definition & Types
APIs have taken center stage in software development, acting as a bridge between different layers of the software and applications, aiding the transfer of data and logic.
What is API?
API or Application Programming Interfaces act as a middle layer connecting two different systems or layers of application, mainly the database and presentation layers. As it is sandwiched between the two layers and is in direct contact with both, it acts as a medium for data exchange and communication between the systems or the layers. In simple terms, an API is a messenger that takes requests and relays them to the system, then returns the system’s response back to the requester.
What is API Testing?
Similar to software testing practices, API testing tests the API for reliability, functionality, and performance. While retaining the same working principle as software testing, it’s somewhat different based on the procedure. Instead of using the standard input interface, API testing uses specialized software to send calls to API and analyze its response. Compared to GUI testing, which focuses mainly on appearance and validates the presentation aspects of a web application, API testing focuses on validating the inherent business logic, security, and data responses.
What Are The Types of API Testing?
It’s the most basic of the API testing and, as the name suggests, aims only at a single request to a single endpoint and for a single response. Due to the simplicity of this type of API testing, unit testing can usually be done manually via the command line or using tools like SoapUI.
As the primary function of API is to transfer data and logic from one component to another, end-to-end API testing aims to validate this flow of data and detect any possible hindrance in between the path. End-to-end API testing is done to validate the API connections to different components and check if the data and information flow smoothly or not.
APIs connect different layers of the system, software, or the application and therefore act as a medium of integration among these different layers. Integration testing aims to test API’s connections with the layers and therefore is the most common form of API testing.
It is obviously necessary to ensure that the API is performing the task it is designed for. Therefore, performance testing is usually done on the API at the last stage of the testing process. However, performance testing is the most extensive and sophisticated of all the API testing types. Its because it requires specific hardware, specialized skills set, and a particular testing environment.
Another crucial stage in any API testing process is security testing. APIs are the backbone of any apps or software these days. If an API is compromised due to security vulnerabilities, the whole system will be at risk of an attack, leading to significant financial losses and tarnished reputation.
A solid API testing environment is essential for designing and developing efficient apps and systems. API testing allows structuring a reliable testing environment, enabling you to identify defects and vulnerabilities at different layers of your app, thereby helping you eliminate them.