def METHOD_NAME(self):
    stream = Stream.define('Custom', y=2)()
    dmap = DynamicMap(lambda y: Curve([1, 2, y]), kdims=['y'], streams=[stream])
    obj, _ = bokeh_renderer._validate(dmap, None)
    _, session = self._launcher(obj, port=6005)
    [(doc, _)] = obj._documents.items()
    cds = session.document.roots[0].select_one({'type': ColumnDataSource})
    self.assertEqual(cds.data['y'][2], 2)
    def run():
        stream.event(y=3)
    doc.add_next_tick_callback(run)
    time.sleep(1)
    cds = self.session.document.roots[0].select_one({'type': ColumnDataSource})
    self.assertEqual(cds.data['y'][2], 3)