code: def test_plotlyjs_version(self):
      path = os.path.join(
          packages_root,
          "javascript",
          "jupyterlab-plotly",
          "package.json",
      )
      with open(path, "rt") as f:
          package_json = json.load(f)
          expected_version = package_json["dependencies"]["plotly.js"]
          if expected_version[0] == "^":
              expected_version = expected_version[1:]
  
      self.assertEqual(
          expected_version, plotly.offline.get_plotlyjs_version()
      )
  
imports: import json
  import os
  from unittest import TestCase
  import pytest
  import plotly
  import plotly.io
  from plotly.io._utils import plotly_cdn_url
label_desc: Use image node_id 18 for calling the PlotlyOfflineTestCase obj's underlying member method code with example usage: obj.test_plotlyjs_version() without return types