How to measure time spent inside Python trio coroutine?

For testing purposes, I would like to measure the time that is spent on blocking execution of a coroutine (i.e, excluding the time for which it is suspended).

For example:

import trio
import time

async def under_test():
   await trio.sleep(2)
   time.sleep(3)

async def measure():
   with measure_blocking_time() as ctx: # or something like that
      await under_test()
   assert ctx.elapsed == 3

trio.run(measure)

How do I do that?

(There seems to be a somewhat hacky way to do this when using asyncio - hopefully it can be done more nicer in Trio?)

belm0/perf-timer solves exactly this problem for threads and Trio, but not asyncio.

The relevant usage snippet from the readme is:

from perf_timer import TrioPerfTimer

@TrioPerfTimer('get thumbnail')
async def get_thumbnail_image(path):
    img = cache.get_thumbnail(path)
    if not thumbnail:
        img = await read_image(path)
        img.decode()
        img.resize(THUMBNAIL_SIZE)
        cache.set_thumbnail(img)
    return img