Method _ensure_fd_no_transport

Lib/test/test_asyncio/utils.py:437–452

(self, fd)

            raise AssertionError(f'{handle._args!r} != {args!r}')

    def _ensure_fd_no_transport(self, fd):
        if not isinstance(fd, int):
            try:
                fd = int(fd.fileno())
            except (AttributeError, TypeError, ValueError):
                # This code matches selectors._fileobj_to_fd function.
                raise ValueError("Invalid file object: "
                                 "{!r}".format(fd)) from None
        try:
            transport = self._transports[fd]
        except KeyError:
            pass
        else:
            raise RuntimeError(
                'File descriptor {!r} is used by transport {!r}'.format(
                    fd, transport))

    def add_reader(self, fd, callback, *args):
        """Add a reader callback."""