API is an acronym for Application Programming Interface. It gives users access to public classes, functions, and member variables for calling them from external applications. It lays down a model for components to being interaction with each other.
API testing comprises of three parts:
- Data-tier (database)
- Business logic tier (PHP/J2EE)
- Presentation tier (UI)
API testing is also a white-box testing method. It makes use of the code and a programming tool to call the API. It ignores the UI layer of the application and validates the path between the client and the API. The client software forwards a call to the API to get the specified return value. API testing examines whether the system is responding with the correct status or not.
API testing got carried out by the testers to confirm the system from end to end. They don’t have permission to get to the source code but can use the API calls. This testing covers authorization, usability, exploratory, automated, and document validation.