code: def test_get_relative_url(self):
      to_files = [
          "index.md",
          "foo/index.md",
          "foo/bar/index.md",
          "foo/bar/baz/index.md",
          "foo.md",
          "foo/bar.md",
          "foo/bar/baz.md",
      ]
      to_file_urls = [
          "index.html",
          "foo/index.html",
          "foo/bar/index.html",
          "foo/bar/baz/index.html",
          "foo.html",
          "foo/bar.html",
          "foo/bar/baz.html",
      ]
  
      from_file = File(
          "img.jpg",
          "/path/to/docs",
          "/path/to/site",
          use_directory_urls=False,
      )
      self.assertEqual(from_file.url, "img.jpg")
  
      expected = [
          "img.jpg",  # img.jpg relative to .
          "../img.jpg",  # img.jpg relative to foo/
          "../../img.jpg",  # img.jpg relative to foo/bar/
          "../../../img.jpg",  # img.jpg relative to foo/bar/baz/
          "img.jpg",  # img.jpg relative to foo.html
          "../img.jpg",  # img.jpg relative to foo/bar.html
          "../../img.jpg",  # img.jpg relative to foo/bar/baz.html
      ]
      for i, filename in enumerate(to_files):
          with self.subTest(
              from_file=from_file.src_path, to_file=filename
          ):
              file = File(
                  filename,
                  "/path/to/docs",
                  "/path/to/site",
                  use_directory_urls=False,
              )
              self.assertEqual(file.url, to_file_urls[i])
              self.assertEqual(
                  from_file.url_relative_to(file.url), expected[i]
              )
              self.assertEqual(
                  from_file.url_relative_to(file), expected[i]
              )
  
      from_file = File(
          "foo/img.jpg",
          "/path/to/docs",
          "/path/to/site",
          use_directory_urls=False,
      )
      self.assertEqual(from_file.url, "foo/img.jpg")
  
      expected = [
          "foo/img.jpg",  # foo/img.jpg relative to .
          "img.jpg",  # foo/img.jpg relative to foo/
          "../img.jpg",  # foo/img.jpg relative to foo/bar/
          "../../img.jpg",  # foo/img.jpg relative to foo/bar/baz/
          "foo/img.jpg",  # foo/img.jpg relative to foo.html
          "img.jpg",  # foo/img.jpg relative to foo/bar.html
          "../img.jpg",  # foo/img.jpg relative to foo/bar/baz.html
      ]
      for i, filename in enumerate(to_files):
          with self.subTest(
              from_file=from_file.src_path, to_file=filename
          ):
              file = File(
                  filename,
                  "/path/to/docs",
                  "/path/to/site",
                  use_directory_urls=False,
              )
              self.assertEqual(file.url, to_file_urls[i])
              self.assertEqual(
                  from_file.url_relative_to(file.url), expected[i]
              )
              self.assertEqual(
                  from_file.url_relative_to(file), expected[i]
              )
  
      from_file = File(
          "index.html",
          "/path/to/docs",
          "/path/to/site",
          use_directory_urls=False,
      )
      self.assertEqual(from_file.url, "index.html")
  
      expected = [
          "index.html",  # index.html relative to .
          "../index.html",  # index.html relative to foo/
          "../../index.html",  # index.html relative to foo/bar/
          "../../../index.html",  # index.html relative to foo/bar/baz/
          "index.html",  # index.html relative to foo.html
          "../index.html",  # index.html relative to foo/bar.html
          "../../index.html",  # index.html relative to foo/bar/baz.html
      ]
      for i, filename in enumerate(to_files):
          with self.subTest(
              from_file=from_file.src_path, to_file=filename
          ):
              file = File(
                  filename,
                  "/path/to/docs",
                  "/path/to/site",
                  use_directory_urls=False,
              )
              self.assertEqual(file.url, to_file_urls[i])
              self.assertEqual(
                  from_file.url_relative_to(file.url), expected[i]
              )
              self.assertEqual(
                  from_file.url_relative_to(file), expected[i]
              )
  
      from_file = File(
          "file.html",
          "/path/to/docs",
          "/path/to/site",
          use_directory_urls=False,
      )
      self.assertEqual(from_file.url, "file.html")
  
      expected = [
          "file.html",  # file.html relative to .
          "../file.html",  # file.html relative to foo/
          "../../file.html",  # file.html relative to foo/bar/
          "../../../file.html",  # file.html relative to foo/bar/baz/
          "file.html",  # file.html relative to foo.html
          "../file.html",  # file.html relative to foo/bar.html
          "../../file.html",  # file.html relative to foo/bar/baz.html
      ]
      for i, filename in enumerate(to_files):
          with self.subTest(
              from_file=from_file.src_path, to_file=filename
          ):
              file = File(
                  filename,
                  "/path/to/docs",
                  "/path/to/site",
                  use_directory_urls=False,
              )
              self.assertEqual(file.url, to_file_urls[i])
              self.assertEqual(
                  from_file.url_relative_to(file.url), expected[i]
              )
              self.assertEqual(
                  from_file.url_relative_to(file), expected[i]
              )
  
imports: import os
  import sys
  import unittest
  from unittest import mock
  from mkdocs.structure.files import File, Files, _sort_files, get_files
  from mkdocs.tests.base import PathAssertionMixin, load_config, tempdir
label_desc: Use image node_id 17 for calling the TestFiles obj's underlying member method code with example usage: obj.test_get_relative_url() without return types