code: def test_mock_open_read_with_argument(self):
      # At one point calling read with an argument was broken
      # for mocks returned by mock_open
      some_data = "foo\nbar\nbaz"
      mock = mock_open(read_data=some_data)
      self.assertEqual(mock().read(10), some_data[:10])
      self.assertEqual(mock().read(10), some_data[:10])
  
      f = mock()
      self.assertEqual(f.read(10), some_data[:10])
      self.assertEqual(f.read(10), some_data[10:])
  
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 13 for calling the TestMockOpen obj's underlying member method code with example usage: obj.test_mock_open_read_with_argument() without return types