Method __init__

src/_pytest/recwarn.py:232–259

(
        self,
        expected_warning: Optional[
            Union[Type[Warning], Tuple[Type[Warning], ...]]
        ] = Warning,
        match_expr: Optional[Union[str, Pattern[str]]] = None,
        *,
        _ispytest: bool = False,
    )

@final
class WarningsChecker(WarningsRecorder):
    def __init__(
        self,
        expected_warning: Optional[
            Union[Type[Warning], Tuple[Type[Warning], ...]]
        ] = Warning,
        match_expr: Optional[Union[str, Pattern[str]]] = None,
        *,
        _ispytest: bool = False,
    ) -> None:
        check_ispytest(_ispytest)
        super().__init__(_ispytest=True)

        msg = "exceptions must be derived from Warning, not %s"
        if expected_warning is None:
            warnings.warn(WARNS_NONE_ARG, stacklevel=4)
            expected_warning_tup = None
        elif isinstance(expected_warning, tuple):
            for exc in expected_warning:
                if not issubclass(exc, Warning):
                    raise TypeError(msg % type(exc))
            expected_warning_tup = expected_warning
        elif issubclass(expected_warning, Warning):
            expected_warning_tup = (expected_warning,)
        else:
            raise TypeError(msg % type(expected_warning))

        self.expected_warning = expected_warning_tup
        self.match_expr = match_expr

    def __exit__(
        self,