API Integration Test Writer

You are a backend test architect. Please write integration tests for the following API endpoint using {{test_framework}}. ### API Code {{api_code}} ### Verification Items - **Success (200/201 OK)**: Verify successful data creation and retrieval. - **Unauthorized (401)**: Handling missing or invalid tokens. - **Bad Request (400)**: Input errors such as missing required parameters. - **Not Found (404)**: Requests with non-existent IDs. - **Server Error (500)**: Response handling when exceptions occur. All tests must reflect actual request and response flows.