code: def test_graph_item():
      node_name, link_source = "test_node_name", "test_link_source"
      node = opts.GraphNode(name=node_name)
      link = opts.GraphLink(source=link_source)
      assert_equal(node_name, node.opts.get("name"))
      assert_equal(link_source, link.opts.get("source"))
  
file_path: pyecharts/test/test_graph.py
imports: import os
  import json
  from unittest.mock import patch
  from nose.tools import assert_equal, assert_in
  from pyecharts import options
  from pyecharts.charts import Graph
label_desc: Use image node_id 6 for calling a global function with example usage: test_graph_item() without return types