[Python] Why does asyncio.run() or loop.run_until_complete() run task that is created but not...

Here is the code.

import asyncio

async def run_test():
print("run1")
await asyncio.sleep(1)
print("run2")

async def main():
print("main1")
loop = asyncio.get_event_loop()
task = loop.create_task(run_test())
#task = asyncio.create_task(run_test())
#task = asyncio.ensure_future(run_test())
print("main2")

print("________________")
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
print("________________")


I'm expecting an output like

________________
main1
main2
________________


as the task is not awaited. But the output is actully

________________
main1
main2
run1
________________


And if I remove async.sleep() in run_test(), it becomes like this:

________________
main1
main2
run1
run2
________________


I've also tried

#task = asyncio.create_task(run_test())
#task = asyncio.ensure_future(run_test())


The result is the same. 3 questions:

1. Why is run_test() running without being awaited?
2. Is there anyway to create a task without putting it into the event loop?
3. Shouldn't run_until_complete() return immediately after main() completes? My guess is that the event loop keeps running runnable tasks after main() completes and return when there were no more runnable tasks. But that conflict with the name "run_until_complete". What is actually happening after main() completes?

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