I am trying to unit test a piece of code:

```
def _parse_results(self, file_name):
    results_file = open(file_name)
    results_data = list(csv.reader(results_file))
    index = len(results_data[1])-1
    results_file.close()
    return float(results_data[1][index])

```

by using mock\_open like so:

```
@mock.patch('path.open', mock.mock_open(read_data='test, test2, test3, test4'))
def test_parse_results(self):
    cut = my_class(emulate=True)
    self.assertEqual(VAL, cut._parse_results('file'))

```

The problem I am running into is that I do not get any data when running csv.reader. If I run results\_file.readlines() I get 'test, test2, test3, test4' which means that mock\_open is working properly. But when I run csv.reader(results\_file) I lose all the data.