Python mocking example

mock_tut.py

from mock import Mock, MagicMock

mock = Mock(return_value=1)
mock(1, 5, animal='dog')  # returns 1 always

m = MagicMock(side_effect=ValueError)
m(1, 2, 3, 4)  # raises valueError

m = Mock()
attrs = {'mocked_method.return_value': 3,
         'mocked_method_raises_exception.side_effect': ZeroDivisionError, }
m.configure_mock(**attrs)
m.mocked_method('Whats up function')  # returns 3 always
m.mocked_method_raises_exception(True, False, 42)  # raises ZeroDivisionError

import requests
m = Mock(spec=requests)  # m is now a mocked request object.
# Every Mock object can run any method, even if you didn't configure it's spec
# we can still go m = Mock() and m.get() for example (get is requests' method).
# But when you do spec=requests, m.method_not_in_requests() will throw error
# "Mock object has no attribute '...'"

## Testing functions
# Function to test
def get_data():
    response = requests.get('http://httpbin.org/get')
    return response.status_code
# Inside the test patch requests.get to return object with status_code 200
with patch.object(requests, 'get') as get_mock:
    get_mock.return_value.status_code = 200
    assert get_data() == 200 # will call mocked get_data with return value of status_code 200