python mock what is return_value in the following

Question

i am very new to python mock and so just trying to understand the same. In the below code what is the difference between 1 and 2 statements indicated below,because in the end i can set mock_response.status_code with either of the statements

   import requests

    def get_data():
        response = requests.get('https://www.somesite.com')
        return response.status_code

    if __name__ == '__main__':
        print get_data()

Now what is the difference between the following codes,

    from call import get_data
    import unittest
    from mock import Mock,patch
    import requests

    class TestCall(unittest.TestCase):
        def test_get_data(self):
            with patch.object(requests,'get') as get_mock:
                1.get_mock.return_value = mock_response = Mock()
                  # OR 
                2.mock_response = get_mock.return_value
                mock_response.status_code = 200
                assert get_data() == 200

    unittest.main()

Sam R. · Accepted Answer · 2017-07-10 01:15:46Z

2

Looking at the docs:

return_value: The value returned when the mock is called. By default this is a new Mock (created on first access). See the return_value attribute.

You are mocking the get function of the requests module. The get method is supposed to return a response object which later you assert its status_code. Therefore you're telling the get mock function to return a mock response. According to the docs, return_value by default returns a Mock object, hence there should be no difference between 1 and 2 except that 1 is explicitly creating a Mock and 2 uses the default behavior.

As a side note, that unit test is testing nothing because you set the status_code on the Mock object and then assert it. It's like:

status_code = 200
assert status_code == 200

answered Jul 10, 2017 at 1:15

Sam R.

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