How can I use unittest.mock for advanced testing scenarios?

How can I use unittest.mock for advanced testing scenarios?

You can use unittest.mock to create complex test cases by mocking objects, methods, and even entire classes.

Can you give me an example of mocking a method in a class?

Sure! You can use @patch decorator to mock a method. For example:

from unittest.mock import patch

class MyClass:
    def method_to_mock(self):
        return 'original'

@patch.object(MyClass, 'method_to_mock', return_value='mocked')
def test_method(mock_method):
    obj = MyClass()
    assert obj.method_to_mock() == 'mocked'

What about testing exceptions with mocks?

You can use side_effect to raise exceptions. For example:

@patch('module.Class.method', side_effect=Exception('error'))
def test_method(mock_method):
    with pytest.raises(Exception):
        obj = Class()
        obj.method()