Allow accessing all arguments by name on mock call objects

Feature or enhancement

Currently, call objects from the unittest.mock library only provide a tuple of positional arguments and a dictionary of keyword arguments passed to the function. It should be possible to enable accessing all arguments by name, not just the keyword arguments. The Signature object can help with this: https://docs.python.org/3/library/inspect.html#introspecting-callables-with-the-signature-object.

Pitch

For more robust and readable testing code.

先閱讀 unittest.mock 的 call 物件行為以及連結的 inspect.Signature 文件。決定如何在現有的位置參數 tuple 和關鍵字參數 dictionary 之外依名稱存取位置參數，然後定義預期的 API 與測試，以示範可讀的具名參數存取方式。