In bpo-32972 we enabled debug mode in IsolatedAsyncioTestCase._setupAsyncioLoop, which may print some warnings that are not that important to tests.
(e.g. Executing <Future ...> took 0.110 seconds)

I personally don't really like it being turn on by default, but if it needs to be so, maybe include it in document would be a good idea.

Add Andrew to nosy list because he was the author.

This print comes from asyncio debug mode when async function is blocked by time longer than 0.1 sec (see loop.slow_callback_duration at loop.slow_callback_duration).
Usually, it is a sign of a problem in user code, e.g. something should be pushed into executor.

A test case is executed in debug mode. I think it is reasonable for the test run, isn't it?

The mode can be disabled by `asyncio.get_running_loop().set_debug(False)` in `asyncSetUp()` method.

> Usually, it is a sign of a problem in user code, e.g. something should be pushed into executor.

Sometimes also happens on low-end CI machines.

And the message is somewhat unclear to me.
I have to grep cpython sources to understand that it is coming from debug mode and it means there is a slow awaitable ... in somewhere, because the displayed file:line is not always the right position.

> A test case is executed in debug mode. I think it is reasonable for the test run, isn't it?

Probably.

> The mode can be disabled by `asyncio.get_running_loop().set_debug(False)` in `asyncSetUp()` method.

Glad to know that. Thanks.

Well, if the reported line is invalid it should be fixed

Hi, is there anything that needs to be fixed or done here?

At first, would be nice to figure out what "invalid line reported" does mean.  
What text is reported and what is expected?

Executing <Handle <TaskWakeupMethWrapper object at 0x10b31ec10>(<Future finis...events.py:418>) created at /.../lib/python3.8/asyncio/queues.py:70> took 0.104 seconds
Executing <Handle <TaskWakeupMethWrapper object at 0x10b31e9d0>(<Future finis...events.py:418>) created at /.../lib/python3.8/asyncio/queues.py:70> took 0.121 seconds

I was expecting it can display the stack of the awaitable.

Thanks for the clarification.
I forgot about this thing; the output can be improved sure.
As a workaround you can use the following hack::

import asyncio.task
asyncio.task.Task = asyncio.task._PyTask

IIRC the pure python version prints a coroutine name at least.

I've assigned myself to never forget about the issue; if somebody wants to fix _CTask and TaskWakeupMethWrapper representation -- you are welcome

I cannot import asyncio.task, so I did this instead:

import asyncio.tasks
asyncio.tasks.Task = asyncio.tasks._PyTask

Then it changed to this:

Executing <Task pending name='Task-1' coro=<IsolatedAsyncioTestCase._asyncioLoopRunner() running at /.../lib/python3.8/unittest/async_case.py:96> wait_for=<Future pending cb=[Task.__wakeup()] created at /.../lib/python3.8/asyncio/base_events.py:418> created at /.../lib/python3.8/unittest/async_case.py:118> took 0.187 seconds

I suppose this means the entire test case is slow?

Slower by percents, not in the factor of times.

I guess for tests it is satisfactory.

The output will be fixed by #38986
Nothing to do here.