docstr: Requests for media files in MediaFileManager should succeed.
docstr_tok: ["Requests","for","media","files","in","MediaFileManager","should","succeed","."]
code: def test_media_file(self) -> None:
      """Requests for media files in MediaFileManager should succeed."""
      # Add a media file and read it back
      url = self.media_file_manager.add(
          b"mock_data", "video/mp4", "mock_coords"
      )
      rsp = self.fetch(url, method="GET")
  
      self.assertEqual(200, rsp.code)
      self.assertEqual(b"mock_data", rsp.body)
      self.assertEqual("video/mp4", rsp.headers["Content-Type"])
      self.assertEqual(
          str(len(b"mock_data")), rsp.headers["Content-Length"]
      )
  
file_path: streamlit/lib/tests/streamlit/web/server/media_file_handler_test.py
imports: from unittest import mock
  from unittest.mock import MagicMock
  import tornado.testing
  import tornado.web
  from parameterized import parameterized
  from typing_extensions import Final
  from streamlit.runtime.media_file_manager import MediaFileManager
  from streamlit.runtime.memory_media_file_storage import MemoryMediaFileStorage
  from streamlit.web.server.media_file_handler import MediaFileHandler
label_desc: Use image node_id 3 for calling the MediaFileHandlerTest obj's underlying member method code with example usage: obj.test_media_file() without return types