code: def test_dunder_iter_data(self):
      # Check that dunder_iter will return all the lines from the fake file.
      mock = mock_open(read_data="foo\nbar\nbaz\n")
      with patch("%s.open" % __name__, mock, create=True):
          h = open("bar")
          lines = [l for l in h]
      self.assertEqual(lines[0], "foo\n")
      self.assertEqual(lines[1], "bar\n")
      self.assertEqual(lines[2], "baz\n")
      self.assertEqual(h.readline(), "")
      with self.assertRaises(StopIteration):
          next(h)
  
imports: import unittest
  from warnings import catch_warnings
  from test.test_unittest.testmock.support import is_instance
  from unittest.mock import MagicMock, Mock, patch, sentinel, mock_open, call
label_desc: Use image node_id 7 for calling the TestMockOpen obj's underlying member method code with example usage: obj.test_dunder_iter_data() without return types