API Testing

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API Testing is a specialized testing technique that focuses on verifying the functionality, reliability, performance, and security of application programming interfaces (APIs). It involves sending requests, analyzing responses, and validating the behavior and data exchange of APIs.

Examples of API Testing

• You can perform API Testing on a social media platform to ensure that the user authentication API securely validates user credentials and returns the appropriate access tokens.
• In an e-commerce application, you conduct API Testing to validate that the product search API accurately retrieves the desired products based on specified criteria.
• For a weather forecasting application, you do API Testing to validate that the weather data API returns accurate and up-to-date information for different geographical locations.
• Popular tools for API Testing include SoapUI, Postman, JMeter, and RestAssured, which provide features for sending API requests, inspecting responses, and automating API tests.

Tips for API Testing

• Understand your API documentation thoroughly to identify the input parameters, expected responses, and error handling mechanisms.
• Design test cases with different scenarios such as valid inputs, invalid inputs, edge cases, and error conditions.
• Validate the response data against the expected results to ensure the API behaves as intended.
• Conduct performance testing on APIs to assess their latency, response time, throughput, and scalability under different workload conditions.

FAQ (interview questions and answers)

1. Do you automate API Testing?
   Yes, API Testing is automated using tools like SoapUI, Postman, and RestAssured. Automation can help in executing repetitive API tests, handling large-scale testing, and integrating API tests into continuous integration/continuous delivery (CI/CD) pipelines.
2. What are the common security aspects to consider in API Testing?
   Validating authentication and authorization mechanisms, testing for input validation and output encoding to prevent injection attacks, ensuring secure transmission of data over HTTPS, and handling error responses securely to avoid information leakage.
3. Is API Testing only applicable for web-based applications?
   No, it can be performed on various types of APIs, including web APIs, RESTful APIs, SOAP APIs, microservices APIs, and APIs used in mobile applications.

Remember to just comment if you have any doubts or queries.