[18.0] fastapi: improve test coverage

[SBillion]

Description generated by Copilot

This pull request adds and improves docstrings for test methods in fastapi/tests/test_fastapi.py and fastapi/tests/test_fastapi_demo.py, providing clear descriptions of each test's purpose and behavior. Additionally, several new tests are introduced to increase coverage of language negotiation, error handling, HTTP methods, and endpoint routing.

The most important changes include:

Test Documentation Improvements:

• Added or enhanced docstrings to nearly all test methods in test_fastapi.py and test_fastapi_demo.py, clarifying the intent and expected behavior of each test. This makes the test suite easier to understand and maintain. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]

Expanded Test Coverage:

• Added new tests in test_fastapi.py for: response content type, language negotiation defaults and error handling, retry logic and validation, exception handling with special characters, concurrent language requests, URL path matching (including edge cases), and HTTP method restrictions.
• Added new tests in test_fastapi_demo.py for: endpoint info, authenticated user info, and exception handling with/without server exception propagation. [1] [2] [3] [4]

Test Robustness and Edge Cases:

• Introduced tests for boundary and error conditions, such as malformed headers, missing or invalid parameters, and concurrent requests, ensuring the application behaves correctly in less common scenarios.

These changes significantly improve the clarity, maintainability, and robustness of the test suite.

[OCA-git-bot]

Hi @lmignon,
some modules you are maintaining are being modified, check this out!