unittest for decorator in python

Question

class BackgroundProcess:

    def background(f):
        from functools import wraps
        @wraps(f)
        def wrapped(*args, **kwargs):
            loop = asyncio.get_event_loop()
            if callable(f):
                return loop.run_in_executor(None, f, *args, **kwargs)
            else:
                raise TypeError('Task must be a callable')    
        return wrapped

class Monitoring

    @BackgroundProcess.background
    def post_monitoring_event_in_background() 
             return ''

How to write test cases for post_monitoring_event_in_background method by mocking @BackgroundProcess.background