Python unittest request session when “with” statement is used

I want to mock requests.session() in unit test. It works when I don’t use with statement, however it fails when I start using it. This is the code I execute:

main.py:

import requests

def parse():
    with requests.session() as s:
        return s.get('foo')

if __name__ == "__main__":
    parse()

test_main.py:

import unittest
import mock
from unittest.mock import patch
from main import parse


class TestDoSessionGet(unittest.TestCase):
    @mock.patch('main.requests.session')
    def test_should_mock_session_get(self, session_mock):
        session_mock.return_value = mock.MagicMock(get=mock.MagicMock(return_value='bar'))
        self.assertEqual(parse(), 'bar')

Answer

Your test setup is ignoring the fact that s comes from the __enter__ method of the context manager class.

You need to mock that call as well

import unittest
from unittest import mock
from main import parse


class TestDoSessionGet(unittest.TestCase):
    @mock.patch('main.requests.session')
    def test_should_mock_session_get(self, session_mock):
        mocked_session = mock.MagicMock()
        mocked_session.__enter__.return_value = mock.MagicMock(get=mock.MagicMock(return_value='bar'))
        session_mock.return_value = mocked_session
        self.assertEqual(parse(), 'bar')