docstr: Test readFile with a file that does not exist
code: def test1(self):
      """Test readFile with a file that does not exist"""
      self.failUnlessXmlError(
          libxml2.readFile,
          ("dummy.xml", None, 0),
          libxml2.treeError,
          domain=libxml2.XML_FROM_IO,
          code=libxml2.XML_IO_LOAD_ERROR,
          message='failed to load external entity "dummy.xml"\n',
          level=libxml2.XML_ERR_WARNING,
          file=None,
          line=0,
      )
  
file_path: turicreate/deps/src/libxml2-2.9.1/python/tests/tstLastError.py
imports: import sys, unittest
  import libxml2
label_desc: Use image node_id 5 for calling the TestCase obj's underlying member method code with example usage: obj.test1() without return types