code: def test_themeriver_basefake_writer(fake_writer):
      data = [
          ["2015/11/08", 10, "DQ"],
          ["2015/11/20", 30, "TY"],
          ["2015/11/08", 21, "SS"],
          ["2015/11/14", 7, "QG"],
          ["2015/11/22", 4, "SY"],
          ["2015/11/20", 26, "DD"],
      ]
      c = ThemeRiver().add(
          ["DQ", "TY", "SS", "QG", "SY", "DD"],
          data,
          singleaxis_opts=opts.SingleAxisOpts(
              type_="time", pos_bottom="10%"
          ),
      )
      c.render()
      _, content = fake_writer.call_args[0]
      assert_equal(c.theme, "white")
      assert_equal(c.renderer, "canvas")
  
imports: from unittest.mock import patch
  from nose.tools import assert_equal
  from pyecharts import options
  from pyecharts.charts import ThemeRiver
label_desc: Use image node_id 1 for calling a global function with example usage: test_themeriver_basefake_writer(fake_writer) without return types