Class InMemoryExampleDatabase

hypothesis/src/hypothesis/database.py:368–415

A non-persistent example database, implemented in terms of an in-memory dictionary. This can be useful if you call a test function several times in a single session, or for testing other database implementations, but because it does not persist between runs we do not recommend it fo

class InMemoryExampleDatabase(ExampleDatabase):
    """A non-persistent example database, implemented in terms of an in-memory
    dictionary.

    This can be useful if you call a test function several times in a single
    session, or for testing other database implementations, but because it
    does not persist between runs we do not recommend it for general use.
    """

    def __init__(self) -> None:
        super().__init__()
        self.data: dict[bytes, set[bytes]] = {}

    def __repr__(self) -> str:
        return f"InMemoryExampleDatabase({self.data!r})"

    def __eq__(self, other: object) -> bool:
        return isinstance(other, InMemoryExampleDatabase) and self.data is other.data

    def fetch(self, key: bytes) -> Iterable[bytes]:
        yield from self.data.get(key, ())

    def save(self, key: bytes, value: bytes) -> None:
        value = bytes(value)
        values = self.data.setdefault(key, set())
        changed = value not in values
        values.add(value)

        if changed:
            self._broadcast_change(("save", (key, value)))

    def delete(self, key: bytes, value: bytes) -> None:
        value = bytes(value)
        values = self.data.get(key, set())
        changed = value in values
        values.discard(value)

        if changed:
            self._broadcast_change(("delete", (key, value)))

    def _start_listening(self) -> None:
        # declare compatibility with the listener api, but do the actual
        # implementation in .delete and .save, since we know we are the only
        # writer to .data.
        pass

    def _stop_listening(self) -> None:
        pass


def _hash(key: bytes) -> str: