In this example I define a very simple client that authenticate with AppNexus API and return the authentication token. In the test file i mock the post() method of the requests library and I make it return a JSON response that I want. The final result is that when I call the authenticate() method, it doesn't really call the remote API, and the r…

appnexus_client.py

import requests
import json

class AppNexusClient(object):
    @staticmethod
    def authenticate(username, password):
        auth_data = {'auth': {'username': username, 'password': password}}
        r = requests.post('https://api.appnexus.com/auth', data = json.dumps(auth_data))
        return r.json()['response']['token']

test_appnexus_client.py

import unittest
import requests
from mock import patch
from appnexus_client import AppNexusClient

class MockResponseValid(object):
    def json(self):
        return self.data

    def __init__(self, data):
        self.status_code = 200
        self.data = data

class AppNexusClientTests(unittest.TestCase):
    def test_authentication(self):
        with patch.object(requests, 'post') as mock_method:
            mock_method.return_value = MockResponseValid({"response": {"token": "AAABBBCCCDDD"}})
            self.assertEqual(AppNexusClient.authenticate('username', 'password'), 'AAABBBCCCDDD')

unittest.main()