code: def test_get_fs():
      from .. import get_fs, register_filesystem
      from ..fsspec_adapter import FsSpecAdapter
  
      class InMemoryFileSystemAdapter(FsSpecAdapter):
          def __init__(self, **kwargs):
              super().__init__("memory", **kwargs)
  
      register_filesystem("memory", InMemoryFileSystemAdapter)
  
      assert isinstance(get_fs("file://"), LocalFileSystem)
      assert isinstance(get_fs("memory://"), InMemoryFileSystemAdapter)
  
      try:
          get_fs("unknown://")
      except ValueError as e:
          assert "Unknown file system type" in e.__str__()
  
file_path: mars/mars/lib/filesystem/tests/test_filesystem.py
imports: import glob
  import os
  import tempfile
  import numpy
  import pytest
  from ....tests.core import require_hadoop
  from ....utils import lazy_import
  from ..None import glob, FileSystem, LocalFileSystem, FSMap
label_desc: Use image node_id 6 for calling a global function with example usage: test_get_fs() without return types