import io
import unittest
from unittest import mock

from mymodule import function_to_test


@mock.patch("builtins.open", create=True)
class FooTest(unittest.TestCase):
    def test_foo(self, _open):
        fake_file = io.StringIO("foo\nbar\n")
        _open.return_value = fake_file
        self.assertEqual(["foo", "bar"], function_to_test())