Add support for running tests with multiple backends

from typing import Any

from typing import Callable

from typing import Coroutine

from typing import Literal

from typing import Tuple

from typing import Union

from unittest import TestCase

from unittest import mock

from warnings import warn

import anyio

try:

	import trio as _  # noqa

	USE_TRIO = True

except ImportError:

	USE_TRIO = False

Backend = Union[Literal['asyncio'], Literal['trio']]

py_version = sys.version_info[:2]

AsyncTestFunc = Callable[..., Coroutine[Any, Any, None]]

TestFunc = Callable[..., None]

def with_anyio(timeout: int = 10) -> Callable[[AsyncTestFunc], TestFunc]:

def with_anyio(*backends: Backend, timeout: int = 10) -> Callable[[AsyncTestFunc], TestFunc]:

	"""

	Create a wrapping decorator to run asynchronous test functions

	"""

	if not backends:

		backends = ('asyncio',)

	def decorator(testfunc: AsyncTestFunc) -> TestFunc:

		async def test_async_wrapper(tc: TestCase, args: Tuple[mock.Mock]) -> None:

				await testfunc(tc, *args)

		@wraps(testfunc)

		def test_wrapper(*args: mock.Mock) -> None:

			anyio.run(test_async_wrapper, args)

		def test_wrapper(tc: TestCase, *args: mock.Mock) -> None:

			for backend in backends:

				if backend == 'trio' and not USE_TRIO:

					warn(

						f"not running {testfunc.__name__} with trio; package is missing",

					)

					continue

				with tc.subTest(f"backend: {backend}"):

					anyio.run(test_async_wrapper, tc, args, backend=backend)

		return test_wrapper