Authentication Testing (OAuth, API Keys)

Summary

Verifying that API authentication is correctly enforced — valid credentials work, invalid ones are rejected, and expired tokens are handled properly — a security-adjacent but standard QA responsibility.

• 1Test an API with valid credentials, invalid credentials, and no credentials, comparing responses.
• 2Learn the basic OAuth flow conceptually, since it's the most common modern API auth scheme.
• 3Understand why testing authentication failure cases is as important as testing successful access.