code: def testErnieChanGldVsGdx(self):
      files = []
      for year in range(2006, 2013):
          for symbol in ["gld", "gdx"]:
              fileName = "%s-%d-yahoofinance.csv" % (symbol, year)
              files.append(os.path.join("samples", "data", fileName))
  
      with common.CopyFiles(files, "."):
          code = """
  from samples import statarb_erniechan
  statarb_erniechan.main(False)
  """
          res = common.run_python_code(code)
  
          self.assertTrue(res.exit_ok(), res.get_output())
          self.assertEqual(
              res.get_output_lines()[-1:],
              common.tail_file("statarb_erniechan.output", 1),
          )
  
imports: import os
  import six
  from testcases import common
label_desc: Use image node_id 1 for calling the SampleStratTestCase obj's underlying member method code with example usage: obj.testErnieChanGldVsGdx() without return types