Mock patch is not working with class in init.py

Question

I'm trying to use patch to return the a Mock from within a method. The basic structure is as follows:

MyCode.py

class MyClass:

    def __init__(self, first_name, last_name):
        self.first = first_name
        self.last = last_name

    def get_greeting(self):
        return 'Hello {f} {l}'.format(f=self.first, l=self.last)


def get_new_greeting(first_name, last_name):
    obj = MyClass(first_name, last_name)
    return obj.get_greeting()


my_code_test.py

import unittest
from mock import Mock, patch
import my_code

class TestMyCode(unittest.TestCase):
    def setUp(self):
        pass

    @patch('my_code.MyClass')
    def test_get_greeting(self, MockClass):
        instance = MockClass.return_value
        mock_greeting = 'Hello Me'
        instance.get_greeting.return_value = mock_greeting

        greeting = my_code.get_new_greeting('john', 'doe')
        self.assertEqual(greeting, mock_greeting)


if __name__ == '__main__':
    unittest.main()

The code above works fine for me. However, when I apply the same pattern to the real code that I'm trying to test, the real object (not the mock one) gets returned in the method being tested. I can't see any differences. The only think that is a bit different is that the real class is defined in a init.py file. I'm not sure if this make a difference or not? Has any seen this before?

Note: the actual lib is twilio 3.3.5 and I'm using Python 2.6.5 and Django 1.3.1 and Mock 0.7.2

You probably need to post the code that isn't working, rather than the code that is. — Daniel Roseman
@DanielRoseman very valid point. The reason that I used this approach was that I figured very few people would have the twilio package and might not want to install it (although this isn't a big deal if you are using virtualenv), and I wanted to show that I understood the basic principle of what I needed to do. Thanks for your reply. — David S

David S David S · Accepted Answer · 2012-01-20T21:25:18

I figured it out. It had nothing to do with __init__.py file. It was (as usual) my fault! :)

Just for anyone that is every trying to use Mock and patch with Twilio and SMS in the future, here is the solution:

I was Mocking the class twilio.rest.TwilioRestClient But, things are chained together and I needed to call patch on the inner class called SmsMessage. So, for my unit test, this works well:

@patch('twilio.rest.resources.SmsMessages')
def test_send_msg_valid_args(self, MockClass):
    instance = MockClass.return_value
    instance.create.return_value = None
    to_number = '+15555555555'
    msg = 'Hello world'
    send_sms(to_number, msg)

    instance.create.assert_called_once_with(to=to_number, body=msg, from_=default_from_number)

note: send_sms is really the function that I'm trying to test. I just wanted to make sure that it was calling twilio as expected and supplying the default_from_number. The value default_from_number is defined in the settings file and not really important for this example.

Mock patch is not working with class in __init__.py

1 Answers

Mock patch is not working with class in init.py