API is known as Application Programming Interface, it enables the exchange of data between two software systems.API testing is entirely different from GUI. GUI testing is working on Presentation layer (User interface) but the API testing is working on Business layer (Application user interface). Here testing would not concentrate on look and feel of the application.
In API testing, application send calls to the API and take the output as system response. To interact with API it needs a application, to drive the API.
- Use testing tool.
- Write own code.
- Check the output value based on the input condition.
- Check the return value, If it does not return anything check the behaviour of the API.
- Check the data structure, updating data structure will have some effect on the system.
API testing approach
- Clearly define the scope of the program.
- Testing methods like equivalence partitioning, boundary value analysis and error guessing are very essential for API testing.
- Input of the API should be defined and planned appropriately.
Types of bugs
- Fail to handle error condition.
- Duplicate functionality.
- Security issues.
- Unused flags.
- Performance issue.
- Responsive data is not structured correctly.
- warning to caller.