What type of testing examines the usability and reliability of an API?

• A. Load Testing
• B. Security Testing
• C. Integration Testing
• D. End to End Testing

Answer: (C)

The focus of testing that examines the usability and reliability of an API is correctly associated with integration testing. This type of testing assesses how well various components of a system work together, including the interactions between an API and the other services or components it connects with. Usability in this context refers to how effectively developers can utilize the API, while reliability pertains to the API's performance under various conditions, including handling expected and unexpected input data.

Integration testing helps ensure that the API functions correctly as part of a larger application, validating that it integrates seamlessly with other services and meets user expectations regarding its exposure of functionalities and reliability during operations. This testing process often simulates real-world scenarios to verify that the API behaves as intended across various integration points, making it critical for evaluating both usability and reliability.

While load testing focuses on how the API performs under heavy traffic conditions, security testing aims at identifying vulnerabilities in the API design and implementation. End-to-end testing, on the other hand, assesses entire workflows through the system, which is broader than just evaluating the API's usability and reliability. Thus, integration testing remains the most relevant approach for this specific examination.