def METHOD_NAME(self, *, stream):
    with patch("faust.streams._current_event") as ce:
        stream._set_current_event(None)
        assert stream.current_event is None
        ce.set.assert_called_once_with(None)
        ce.set.reset_mock()
        with patch("weakref.ref") as ref:
            event = Mock(name="event")
            stream._set_current_event(event)
            assert stream.current_event is event
            ce.set.assert_called_once_with(ref.return_value)
            ref.assert_called_once_with(event)