如何使用 monkeypatch 模拟请求响应

Question

I am trying to mock the response of api call with pytest in using monkeypatch but without success.

In a file functions.py, I have a function call an external API to get data in json format and I want to test this function

   def api_call(url, token):
    try:
        headers = {"Authorization": "Bearer %s" % token['accessToken']}
        session = requests.Session()
        response = session.get(url, headers=headers)
        json_data = response.json()
        return json_data
    except Exception as err:
        print(f'Other error occurred: {err}')

My test function in file test_functions.py:

from lib import requests
import functions as extfunction

class MockResponse:
    def __init__(self, json_data):
        self.json_data = json_data

    def json(self):
        return self.json_data

def test_api_call_get(monkeypatch):
    fake_token = {'accessToken' : 'djksjdskjdsjdsljdsmqqqq'}

    def mock_get(*args, **kwargs):
        return MockResponse({'results': 'test', 'total_sum' : 2000})

    monkeypatch.setattr(requests, 'get', mock_get)

    # extfunction.api_call, which contains requests.get, uses the monkeypatch
    fake_url = 'https://api-test/v2'
    response = extfunction.api_call(fake_url, fake_token)

    assert response['results'] == 'test'
    assert response['total_sum'] == 2000

During test execution, my function api_call (using requests with Get Method) is not mocked and I have an error because function is really called with fake parameters (such as fake_token)

How can I do to fake my response?

Thanks

Answer 1

You should use the responses library, which is made for this purpose.

A code snippet would look like:

import functions as extfunction

import responses

@responses.activate
def test_api_call_get():
    fake_token = {'accessToken' : 'djksjdskjdsjdsljdsmqqqq'}

    responses.add(responses.GET, 'https://api-test/v2',
                  json={'results': 'test', 'total_sum' : 2000})


    # extfunction.api_call, which contains requests.get, uses the monkeypatch
    fake_url = 'https://api-test/v2'
    response = extfunction.api_call(fake_url, fake_token)

    assert response['results'] == 'test'
    assert response['total_sum'] == 2000

Answer 2

The monkeypatch is modifying the requests function get(), as in

response = requests.get(url, headers=headers)

When you are using requests.Session().get()

This can be monkeypatched by modifying the Session class instead of the requests module.

monkeypatch.setattr(requests.Session, 'get', mock_get)