Await an async function in Python debugger

Question

Is it possible to await arbitrary calls to an async function when inside a Python debugger?

Say I have the following code in some main.py file:

import asyncio

async def bar(x):
    return x + 1

async def foo():
    import ipdb; ipdb.set_trace()

asyncio.run(foo())

Now I want to test calling bar() with some argument inside the debugger to test the results. The following happens:

$ python3 main.py
> /Users/user/test/main.py(8)foo()
      7     import ipdb; ipdb.set_trace()
----> 8     return None
      9

ipdb> bar(1)
<coroutine object bar at 0x10404ae60>
main.py:1: RuntimeWarning: coroutine 'bar' was never awaited
  import asyncio
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
ipdb> await bar(1)
*** SyntaxError: 'await' outside function

Of course, I can get around this by having x = await bar(1) above my ipdb.set_trace(), and then inspecting the results, but then I can't try calling my functions in real time while the debugger is active.

Answer 1

Seems like there's starting to be more support for this feature since Python 3.8. In particular, look at this issue bpo-37028

If you're still on Python 3.7, maybe aiomonitor could have something that supports this feature to a certain extent.

Answer 2

Here a modified version of what I posted at https://stackoverflow.com/a/67847257/893857 since it also solves this problem.

I found a solution using nest_asyncio. If one has the following async example script:

import asyncio
import nest_asyncio


async def bar(x):
    return x + 1

async def foo():
    import ipdb; ipdb.set_trace()


if __name__=="__main__":
    loop = asyncio.get_event_loop()
    nest_asyncio.apply(loop)
    loop.run_until_complete(foo())

One can then do:

      8 async def foo():
----> 9     import ipdb; ipdb.set_trace()
     10 

ipdb> loop = asyncio.get_event_loop()
ipdb> loop.run_until_complete(bar(1))
2

Admittedly it is a bit more tedious then await bar(1) but it gets the job done. Hopefully a more elegant solution will come up in the future.