unittest.mock
unittest.mock patches dependencies so tests run without real I/O, network, or database calls.
Python
Intermediate
4 min read
Mocking with unittest.mock
Example
from unittest.mock import patch, MagicMock
def test_sends_email():
with patch("myapp.services.send_email") as mock_send:
mock_send.return_value = True
result = register_user("alice@example.com")
mock_send.assert_called_once_with("alice@example.com", subject="Welcome")
assert result["status"] == "ok"
@patch("myapp.api.requests.get")
def test_fetch_user(mock_get):
mock_get.return_value = MagicMock(status_code=200)
mock_get.return_value.json.return_value = {"id": 1, "name": "Alice"}
user = fetch_user(1)
assert user["name"] == "Alice" Pro Tip
Patch the name as imported, not where defined: patch("myapp.views.requests.get") not "requests.get".