Method _assert_state

src/_pytest/capture.py:512–517

(self, op: str, states: tuple[str, ...])

        )

    def _assert_state(self, op: str, states: tuple[str, ...]) -> None:
        assert self._state in states, (
            "cannot {} in state {!r}: expected one of {}".format(
                op, self._state, ", ".join(states)
            )
        )

    def start(self) -> None:
        """Start capturing on targetfd using memorized tmpfile."""