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gh-120284: Enhance asyncio.Runner's run() method to accept more object types #120566

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Sep 26, 2024
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30 changes: 22 additions & 8 deletions Doc/library/asyncio-runner.rst
Original file line number Diff line number Diff line change
Expand Up @@ -24,11 +24,13 @@ Running an asyncio Program

.. function:: run(coro, *, debug=None, loop_factory=None)

Execute the :term:`coroutine` *coro* and return the result.
Execute *coro* in an asyncio event loop and return the result.

This function runs the passed coroutine, taking care of
managing the asyncio event loop, *finalizing asynchronous
generators*, and closing the executor.
The argument can be any awaitable object.

This function runs the awaitable, taking care of managing the
asyncio event loop, *finalizing asynchronous generators*, and
closing the executor.

This function cannot be called when another asyncio event loop is
running in the same thread.
Expand Down Expand Up @@ -70,6 +72,10 @@ Running an asyncio Program

Added *loop_factory* parameter.

.. versionchanged:: 3.14

*coro* can be any awaitable object.


Runner context manager
======================
Expand Down Expand Up @@ -104,17 +110,25 @@ Runner context manager

.. method:: run(coro, *, context=None)

Run a :term:`coroutine <coroutine>` *coro* in the embedded loop.
Execute *coro* in the embedded event loop.

The argument can be any awaitable object.

Return the coroutine's result or raise its exception.
If the argument is a coroutine, it is wrapped in a Task.

An optional keyword-only *context* argument allows specifying a
custom :class:`contextvars.Context` for the *coro* to run in.
The runner's default context is used if ``None``.
custom :class:`contextvars.Context` for the code to run in.
The runner's default context is used if context is ``None``.

Returns the awaitable's result or raises an exception.

This function cannot be called when another asyncio event loop is
running in the same thread.

.. versionchanged:: 3.14

*coro* can be any awaitable object.

.. method:: close()

Close the runner.
Expand Down
17 changes: 13 additions & 4 deletions Lib/asyncio/runners.py
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
import contextvars
import enum
import functools
import inspect
import threading
import signal
from . import coroutines
Expand Down Expand Up @@ -84,19 +85,27 @@ def get_loop(self):
return self._loop

def run(self, coro, *, context=None):
"""Run a coroutine inside the embedded event loop."""
if not coroutines.iscoroutine(coro):
raise ValueError("a coroutine was expected, got {!r}".format(coro))

"""Run code in the embedded event loop."""
if events._get_running_loop() is not None:
# fail fast with short traceback
raise RuntimeError(
"Runner.run() cannot be called from a running event loop")

self._lazy_init()

if not coroutines.iscoroutine(coro):
if inspect.isawaitable(coro):
async def _wrap_awaitable(awaitable):
return await awaitable

coro = _wrap_awaitable(coro)
else:
raise TypeError('An asyncio.Future, a coroutine or an '
'awaitable is required')

if context is None:
context = self._context

task = self._loop.create_task(coro, context=context)

if (threading.current_thread() is threading.main_thread()
Expand Down
29 changes: 19 additions & 10 deletions Lib/test/test_asyncio/test_runners.py
Original file line number Diff line number Diff line change
Expand Up @@ -93,8 +93,8 @@ async def main():
def test_asyncio_run_only_coro(self):
for o in {1, lambda: None}:
with self.subTest(obj=o), \
self.assertRaisesRegex(ValueError,
'a coroutine was expected'):
self.assertRaisesRegex(TypeError,
'an awaitable is required'):
asyncio.run(o)

def test_asyncio_run_debug(self):
Expand Down Expand Up @@ -319,19 +319,28 @@ async def f():
def test_run_non_coro(self):
with asyncio.Runner() as runner:
with self.assertRaisesRegex(
ValueError,
"a coroutine was expected"
TypeError,
"an awaitable is required"
):
runner.run(123)

def test_run_future(self):
with asyncio.Runner() as runner:
with self.assertRaisesRegex(
ValueError,
"a coroutine was expected"
):
fut = runner.get_loop().create_future()
runner.run(fut)
fut = runner.get_loop().create_future()
fut.set_result('done')
self.assertEqual('done', runner.run(fut))

def test_run_awaitable(self):
class MyAwaitable:
def __await__(self):
return self.run().__await__()

@staticmethod
async def run():
return 'done'

with asyncio.Runner() as runner:
self.assertEqual('done', runner.run(MyAwaitable()))

def test_explicit_close(self):
runner = asyncio.Runner()
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Allow :meth:`asyncio.Runner.run` to accept :term:`awaitable`
objects instead of simply :term:`coroutine`\s.
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