CODEWITHSUNDEEP
python-3.xmockingpython-mock
timmy78h
timmy78h

Reputation: 193

Mocking a method's return value does not work

While testing the create_response method, I cannot seem to mock the return value of the get_external_response method.

/foo/response

from abc import ABCMeta, abstractmethod


def create_response(url, type):
    query = create_query(url, type)
    external_response = get_external_response(query)  <-- what I want to mock
    return external_response

def create_query(url, type):
    cc = MyFactory
    return cc.get_concrete_class(url, type)

def get_external_response(cc):
    return cc.make_query()


class MyAbstractClass(metaclass=ABCMeta):
    def __init__(self, url, type):
        self.url = url
        self.type = type
        self.query = self.make_query()

    @abstractmethod
    def make_query(self):
        pass

class MyFactory:
    @staticmethod
    def get_concrete_class(url, type):
        if type == 'A':
            return MyClass(url, type)
        else:
            print("not valid type")

class MyClass(MyAbstractClass):
    def __init__(self, url, type):
        super().__init__(url, type)

    def make_query(self):
        return self.url + self.type


if __name__ == '__main__':
    result = create_response('www.stackoverflow.com', 'A')
    print(result)

If I run the above, I get the expected www.stackoverflow.comA.

But if try to mock the return value of get_external_response, it does not seem to do anything: it still returns www.stackoverflow.comA and the assertion below fails.

/foo/test_response

from foo.response import create_response
import pytest
from unittest import mock


def test_create_response():
    mock_external_response = mock.Mock()
    mock_external_response.create_flask_response.return_value = 'www'

    result = create_response('www.stackoverflow.com', 'A')
    assert result == 'www'

I do not understand why the return value is not set since when the create_response is called, it will eventually reach the point of calling the create_flask_response which, if I am not mistaken, should return www given that I have mocked it.

Can someone explain what I am doing wrong?

Upvotes: 7

Views: 12439

Answers (1)

cischa
cischa

Reputation: 424

I noticed that you are creating a Mock object inside of a function, but are not actually using the Mock. It looks like you need to patch the function where it is used to use the Mock.

/foo/test_response

@mock.patch('foo.response.get_external_response')
def test_create_response(mock_get_external_reponse):
    mock_get_external_response.return_value = 'www'         # This is a Mock object, but will be used as a patch over the actual function where it is used

    result = create_response('www.stackoverflow.com', 'A')
    assert result == 'www'

Quick links to relevant documentation sections for convenience:

Intro to mocking and patching: https://docs.python.org/3/library/unittest.mock.html#quick-guide

Patch specifically here: https://docs.python.org/3/library/unittest.mock.html#unittest.mock.patch

Upvotes: 4

Related Questions