[Tests] RuntimeError: There is no current event loop in thread 'MainThread'

[drew2a]

https://github.com/Tribler/tribler/runs/5988589743?check_suite_focus=true

____________________ test_start_tribler_core_no_exceptions _____________________

mocked_core_session = <AsyncMock name='core_session' id='4803055920'>

    @patch('tribler.core.logger.logger.load_logger_config', new=MagicMock())
    @patch('tribler.core.start_core.set_process_priority', new=MagicMock())
    @patch('tribler.core.start_core.check_and_enable_code_tracing', new=MagicMock())
    @patch('asyncio.get_event_loop', new=MagicMock())
    @patch('tribler.core.start_core.TriblerConfig.load', new=MagicMock())
    @patch('tribler.core.start_core.core_session')
    def test_start_tribler_core_no_exceptions(mocked_core_session):
        # test that base logic of tribler core runs without exceptions
>       run_tribler_core_session(1, 'key', Path('.'), False)

src/tribler/core/tests/test_start_core.py:18: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
src/tribler/core/start_core.py:155: in run_tribler_core_session
    loop.run_until_complete(core_session(config, components=list(components_gen(config))))
src/tribler/core/start_core.py:51: in components_gen
    yield ReporterComponent()
src/tribler/core/components/base.py:204: in __init__
    self.started_event = Event()
../../../hostedtoolcache/Python/3.8.12/x64/lib/python3.8/asyncio/locks.py:[260](https://github.com/Tribler/tribler/runs/5988589743?check_suite_focus=true#step:7:260): in __init__
    self._loop = events.get_event_loop()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <asyncio.unix_events._UnixDefaultEventLoopPolicy object at 0x1203b5a30>

    def get_event_loop(self):
        """Get the event loop for the current context.
    
        Returns an instance of EventLoop or raises an exception.
        """
        if (self._local._loop is None and
                not self._local._set_called and
                isinstance(threading.current_thread(), threading._MainThread)):
            self.set_event_loop(self.new_event_loop())
    
        if self._local._loop is None:
>           raise RuntimeError('There is no current event loop in thread %r.'
                               % threading.current_thread().name)
E           RuntimeError: There is no current event loop in thread 'MainThread'.

../../../hostedtoolcache/Python/3.8.12/x64/lib/python3.8/asyncio/events.py:639: RuntimeError

Probably related to #6176

[drew2a]

Could be helpful:

• https://stackoverflow.com/questions/66583461/pytest-runtimeerror-there-is-no-current-event-loop-in-thread-mainthread
• No event loop in the thread 'MainThread' when using test_client fixture aio-libs/aiohttp#1069
• 0.6.0 version causing test failures with: There is no current event loop in thread 'MainThread' pytest-dev/pytest-asyncio#54