Method _for_parametrize

src/_pytest/mark/structures.py:193–243

(
        cls,
        argnames: str | Sequence[str],
        argvalues: Iterable[ParameterSet | Sequence[object] | object],
        func,
        config: Config,
        nodeid: str,
    )

    @classmethod
    def _for_parametrize(
        cls,
        argnames: str | Sequence[str],
        argvalues: Iterable[ParameterSet | Sequence[object] | object],
        func,
        config: Config,
        nodeid: str,
    ) -> tuple[Sequence[str], list[ParameterSet]]:
        if not isinstance(argvalues, Collection):
            warnings.warn(
                PARAMETRIZE_NON_COLLECTION_ITERABLE.format(
                    nodeid=nodeid,
                    type_name=type(argvalues).__name__,
                ),
                stacklevel=3,
            )

        argnames, force_tuple = cls._parse_parametrize_args(argnames, argvalues)
        parameters = cls._parse_parametrize_parameters(argvalues, force_tuple)
        del argvalues

        if parameters:
            # Check all parameter sets have the correct number of values.
            for param in parameters:
                if len(param.values) != len(argnames):
                    msg = (
                        '{nodeid}: in "parametrize" the number of names ({names_len}):\n'
                        "  {names}\n"
                        "must be equal to the number of values ({values_len}):\n"
                        "  {values}"
                    )
                    fail(
                        msg.format(
                            nodeid=nodeid,
                            values=param.values,
                            names=argnames,
                            names_len=len(argnames),
                            values_len=len(param.values),
                        ),
                        pytrace=False,
                    )
        else:
            # Empty parameter set (likely computed at runtime): create a single
            # parameter set with NOTSET values, with the "empty parameter set" mark applied to it.
            mark = get_empty_parameterset_mark(config, argnames, func)
            parameters.append(
                ParameterSet(
                    values=(NOTSET,) * len(argnames), marks=[mark], id="NOTSET"
                )
            )
        return argnames, parameters


@final