The documentation states that "This method is different from inspect.iscoroutine() because it returns True for generator-based coroutines decorated with @coroutine."

It seems to be wrong, a method written as follow:

def test(): yield 1

will be evaluated as a coroutine by asyncio.iscoroutine(), even if not decorated. The old doc stated "Return True if obj is a coroutine object, which may be based on a generator or an async def coroutine.", which seems more correct.