Python Testing with pytest, Second Edition: Typing mistake (page 13)

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In the Card class definition, the type hints for the summary, owner, and id attributes are currently specified as str, str, and int respectively, with default values of None.

@dataclass
class Card:
    """
    Represents a card with a name, description, and an optional image URL.
    """

    owner: str = None
    summary: str = None
    state: str = "todo"
    id: int = field(default=None, compare=False)

This is a minor mistake. To accurately reflect that these fields are optional and can be None, they should be defined using Optional from the typing module. The corrected type hints are:

  • owner should be Optional[str]
  • summary should be Optional[str]
  • id should be Optional[int]

The corrected class definition would appear as follows (assuming from typing import Optional is present):

from typing import Optional

@dataclass
class Card:
    """
    Represents a card with a name, description, and an optional image URL.
    """

    owner: Optional[str] = None
    summary: Optional[str] = None
    state: str = "todo"
    id: Optional[int] = field(default=None, compare=False)