Class Stash

src/_pytest/stash.py:27–112

r"""``Stash`` is a type-safe heterogeneous mutable mapping that allows keys and value types to be defined separately from where it (the ``Stash``) is created. Usually you will be given an object which has a ``Stash``, for example :class:`~pytest.Config` or a :class:`~_pytest.nodes.N

class Stash:
    r"""``Stash`` is a type-safe heterogeneous mutable mapping that
    allows keys and value types to be defined separately from
    where it (the ``Stash``) is created.

    Usually you will be given an object which has a ``Stash``, for example
    :class:`~pytest.Config` or a :class:`~_pytest.nodes.Node`:

    .. code-block:: python

        stash: Stash = some_object.stash

    If a module or plugin wants to store data in this ``Stash``, it creates
    :class:`StashKey`\s for its keys (at the module level):

    .. code-block:: python

        # At the top-level of the module
        some_str_key = StashKey[str]()
        some_bool_key = StashKey[bool]()

    To store information:

    .. code-block:: python

        # Value type must match the key.
        stash[some_str_key] = "value"
        stash[some_bool_key] = True

    To retrieve the information:

    .. code-block:: python

        # The static type of some_str is str.
        some_str = stash[some_str_key]
        # The static type of some_bool is bool.
        some_bool = stash[some_bool_key]
    """

    __slots__ = ("_storage",)

    def __init__(self) -> None:
        self._storage: Dict[StashKey[Any], object] = {}

    def __setitem__(self, key: StashKey[T], value: T) -> None:
        """Set a value for key."""
        self._storage[key] = value

    def __getitem__(self, key: StashKey[T]) -> T:
        """Get the value for key.

        Raises ``KeyError`` if the key wasn't set before.
        """
        return cast(T, self._storage[key])

    def get(self, key: StashKey[T], default: D) -> Union[T, D]:
        """Get the value for key, or return default if the key wasn't set
        before."""