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To mock an imported function with Jest we use the jest. mock() function. jest. mock() is called with one required argument - the import path of the module we're mocking.
How do we mock in Python? Mocking in Python is done by using patch to hijack an API function or object creation call. When patch intercepts a call, it returns a MagicMock object by default. By setting properties on the MagicMock object, you can mock the API call to return any value you want or raise an Exception .
Just assign the exception to side_effect instead: mockedObj. raiseError. side_effect = Exception("Test") . You don't have to no: and his edit has a third way of doing it where he is making a Mock with the side effect set, but its still a valid, and good thing to know how to do in testing.
mock is a library for testing in Python. It allows you to replace parts of your system under test with mock objects and make assertions about how they have been used. unittest. mock provides a core Mock class removing the need to create a host of stubs throughout your test suite.
When you are using the patch decorator from the unittest.mock package you are patching it in the namespace that is under test (in this case app.mocking.get_user_name), not the namespace the function is imported from (in this case app.my_module.get_user_name).
To do what you describe with @patch try something like the below:
from mock import patch
from app.mocking import test_method
class MockingTestTestCase(unittest.TestCase):
@patch('app.mocking.get_user_name')
def test_mock_stubs(self, test_patch):
test_patch.return_value = 'Mocked This Silly'
ret = test_method()
self.assertEqual(ret, 'Mocked This Silly')
The standard library documentation includes a useful section describing this.
While Matti John's answer solves your issue (and helped me too, thanks!), I would, however, suggest localizing the replacement of the original 'get_user_name' function with the mocked one. This will allow you to control when the function is replaced and when it isn't. Also, this will allow you to make several replacements in the same test. In order to do so, use the 'with' statment in a pretty simillar manner:
from mock import patch
class MockingTestTestCase(unittest.TestCase):
def test_mock_stubs(self):
with patch('app.mocking.get_user_name', return_value = 'Mocked This Silly'):
ret = test_method()
self.assertEqual(ret, 'Mocked This Silly')
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