It is a type of testing which validates APIs. Checks functionality, reliability, performance, and security of programming interfaces. Mainly concentrates on the business logic layer of the software architecture.

Benefits:

– Early testing

– Easier Test Maintenance

– Faster Test Execution

– Greater coverage

Common API Test Cases:

1. Status: the correct response code was returned

2. Performance: the response was returned within a certain time

3. Syntax: the content type of the returned content was as expected

4. Error handling: the server rejects incorrect input

5. Error detection: negative testing to identify exceptions and race conditions

6. Schema: the response payload conforms to an expected structure or format

7. Functional: the server returns a predictable value based on the input condition

8. Security checks: SQL injections do not result in data leakage

Different API Testing Tools:

Postman: Postman is a scalable API testing tool that quickly integrates into CI/CD pipeline and makes it easy to create, share, test and document APIs

Soap UI: It is a leading Functional Testing tool for SOAP and REST testing. SoapUI allows you to easily and rapidly create and execute automated functional, regression, and load tests.

Katalon Studio: It is a comprehensive codeless test automation tool. Katalon Studio supports API, web, desktop, and mobile application testing.

Tricentis Tosca: It simplifies the transition from UI testing to API testing—allowing any tester to rapidly create API tests from an intuitive business-readable interface.

RestAssured: It is a Java-based library that is used to test RESTful Web Services. This library behaves like a headless Client to access REST web services.

POSTMAN vs. SOAP UI vs. Katalon