code: def test_ValidFile(self):
      local_file = valid_textfile(self.tmpdir)
      fh = self.ds.open(local_file)
      assert_(fh)
      fh.close()
  
imports: import os
  import pytest
  from tempfile import mkdtemp, mkstemp, NamedTemporaryFile
  from shutil import rmtree
  import numpy.lib._datasource
  from numpy.testing import assert_, assert_equal, assert_raises
  import urllib.request
  from urllib.parse import urlparse
  from urllib.error import URLError
label_desc: Use image node_id 6 for calling the TestDataSourceOpen obj's underlying member method code with example usage: obj.test_ValidFile() without return types