PySecretHandshake/tests/helpers.py

# SPDX-License-Identifier: MIT
#
# Copyright (c) 2017 PySecretHandshake contributors (see AUTHORS for more details)
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"""Helper utilities for testing"""

from asyncio import StreamReader, StreamWriter
from io import BytesIO
from typing import AsyncIterable, List, Optional, TypeVar

T = TypeVar("T")


class AsyncBuffer(BytesIO, StreamReader, StreamWriter):  # type: ignore[misc]
    """Just a BytesIO with an async read method."""

    async def read(  # type: ignore[override] # pylint: disable=invalid-overridden-method
        self, n: Optional[int] = None
    ) -> Optional[bytes]:
        v = super().read(n)

        return v

    readexactly = read  # type: ignore[assignment]

    def append(self, data: bytes) -> None:
        """Append data to the buffer without changing the current position."""

        pos = self.tell()
        self.write(data)
        self.seek(pos)


async def async_comprehend(generator: AsyncIterable[T]) -> List[T]:
    """Emulate ``[elem async for elem in generator]``."""

    results = []

    async for msg in generator:
        results.append(msg)

    return results