code: def test_nav_no_title(self):
      nav_cfg = [
          "index.md",
          {"About": "about.md"},
      ]
      expected = dedent(
          """
              Page(title=[blank], url='/')
              Page(title='About', url='/about/')
              """
      )
      cfg = load_config(nav=nav_cfg, site_url="http://example.com/")
      fs = [
          File(
              nav_cfg[0],
              cfg.docs_dir,
              cfg.site_dir,
              cfg.use_directory_urls,
          ),
          File(
              nav_cfg[1]["About"],
              cfg.docs_dir,
              cfg.site_dir,
              cfg.use_directory_urls,
          ),
      ]
      files = Files(fs)
      site_navigation = get_navigation(files, cfg)
      self.assertEqual(str(site_navigation).strip(), expected)
      self.assertEqual(len(site_navigation.items), 2)
      self.assertEqual(len(site_navigation.pages), 2)
  
imports: import sys
  import unittest
  from mkdocs.structure.files import File, Files, set_exclusions
  from mkdocs.structure.nav import Section, _get_by_type, get_navigation
  from mkdocs.structure.pages import Page
  from mkdocs.tests.base import dedent, load_config
label_desc: Use image node_id 4 for calling the SiteNavigationTests obj's underlying member method code with example usage: obj.test_nav_no_title() without return types