如何模拟请求和响应？

Question

I am trying to use Pythons mock package to mock Pythons requests module. What are the basic calls to get me working in below scenario?

In my views.py, I have a function that makes variety of requests.get() calls with different response each time

def myview(request):
  res1 = requests.get('aurl')
  res2 = request.get('burl')
  res3 = request.get('curl')

In my test class I want to do something like this but cannot figure out exact method calls

Step 1:

# Mock the requests module
# when mockedRequests.get('aurl') is called then return 'a response'
# when mockedRequests.get('burl') is called then return 'b response'
# when mockedRequests.get('curl') is called then return 'c response'

Step 2:

Call my view

Step 3:

verify response contains 'a response', 'b response', 'c response'

How can I complete Step 1 (mocking the requests module)?

Answer 1

This is how you can do it (you can run this file as-is):

import requests
import unittest
from unittest import mock

# This is the class we want to test
class MyGreatClass:
    def fetch_json(self, url):
        response = requests.get(url)
        return response.json()

# This method will be used by the mock to replace requests.get
def mocked_requests_get(*args, **kwargs):
    class MockResponse:
        def __init__(self, json_data, status_code):
            self.json_data = json_data
            self.status_code = status_code

        def json(self):
            return self.json_data

    if args[0] == 'http://someurl.com/test.json':
        return MockResponse({"key1": "value1"}, 200)
    elif args[0] == 'http://someotherurl.com/anothertest.json':
        return MockResponse({"key2": "value2"}, 200)

    return MockResponse(None, 404)

# Our test case class
class MyGreatClassTestCase(unittest.TestCase):

    # We patch 'requests.get' with our own method. The mock object is passed in to our test case method.
    @mock.patch('requests.get', side_effect=mocked_requests_get)
    def test_fetch(self, mock_get):
        # Assert requests.get calls
        mgc = MyGreatClass()
        json_data = mgc.fetch_json('http://someurl.com/test.json')
        self.assertEqual(json_data, {"key1": "value1"})
        json_data = mgc.fetch_json('http://someotherurl.com/anothertest.json')
        self.assertEqual(json_data, {"key2": "value2"})
        json_data = mgc.fetch_json('http://nonexistenturl.com/cantfindme.json')
        self.assertIsNone(json_data)

        # We can even assert that our mocked method was called with the right parameters
        self.assertIn(mock.call('http://someurl.com/test.json'), mock_get.call_args_list)
        self.assertIn(mock.call('http://someotherurl.com/anothertest.json'), mock_get.call_args_list)

        self.assertEqual(len(mock_get.call_args_list), 3)

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

Important Note: If your MyGreatClass class lives in a different package, say my.great.package , you have to mock my.great.package.requests.get instead of just 'request.get'. In that case your test case would look like this:

import unittest
from unittest import mock
from my.great.package import MyGreatClass

# This method will be used by the mock to replace requests.get
def mocked_requests_get(*args, **kwargs):
    # Same as above


class MyGreatClassTestCase(unittest.TestCase):

    # Now we must patch 'my.great.package.requests.get'
    @mock.patch('my.great.package.requests.get', side_effect=mocked_requests_get)
    def test_fetch(self, mock_get):
        # Same as above

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

Enjoy!

Answer 2

Try using the responses library . Here is an example from their documentation :

import responses
import requests

@responses.activate
def test_simple():
    responses.add(responses.GET, 'http://twitter.com/api/1/foobar',
                  json={'error': 'not found'}, status=404)

    resp = requests.get('http://twitter.com/api/1/foobar')

    assert resp.json() == {"error": "not found"}

    assert len(responses.calls) == 1
    assert responses.calls[0].request.url == 'http://twitter.com/api/1/foobar'
    assert responses.calls[0].response.text == '{"error": "not found"}'

It provides quite a nice convenience over setting up all the mocking yourself.

There's also HTTPretty :

It's not specific to requests library, more powerful in some ways though I found it doesn't lend itself so well to inspecting the requests that it intercepted, which responses does quite easily

There's also httmock .

A new library gaining popularity recently over the venerable requests is httpx , which adds first-class support for async. A mocking library for httpx is: https://github.com/lundberg/respx

Answer 3

Here is what worked for me:

import mock
@mock.patch('requests.get', mock.Mock(side_effect = lambda k:{'aurl': 'a response', 'burl' : 'b response'}.get(k, 'unhandled request %s'%k)))

Answer 4

I used requests-mock for writing tests for separate module:

# module.py
import requests

class A():

    def get_response(self, url):
        response = requests.get(url)
        return response.text

And the tests:

# tests.py
import requests_mock
import unittest

from module import A


class TestAPI(unittest.TestCase):

    @requests_mock.mock()
    def test_get_response(self, m):
        a = A()
        m.get('http://aurl.com', text='a response')
        self.assertEqual(a.get_response('http://aurl.com'), 'a response')
        m.get('http://burl.com', text='b response')
        self.assertEqual(a.get_response('http://burl.com'), 'b response')
        m.get('http://curl.com', text='c response')
        self.assertEqual(a.get_response('http://curl.com'), 'c response')

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

Answer 5

this is how you mock requests.post, change it to your http method

@patch.object(requests, 'post')
def your_test_method(self, mockpost):
    mockresponse = Mock()
    mockpost.return_value = mockresponse
    mockresponse.text = 'mock return'

    #call your target method now

Answer 6

Here is a solution with requests Response class. It is cleaner IMHO.

import json
from unittest.mock import patch
from requests.models import Response

def mocked_requests_get(*args, **kwargs):
    response_content = None
    request_url = kwargs.get('url', None)
    if request_url == 'aurl':
        response_content = json.dumps('a response')
    elif request_url == 'burl':
        response_content = json.dumps('b response')
    elif request_url == 'curl':
        response_content = json.dumps('c response')
    response = Response()
    response.status_code = 200
    response._content = str.encode(response_content)
    return response

@mock.patch('requests.get', side_effect=mocked_requests_get)
def test_fetch(self, mock_get):
     response = requests.get(url='aurl')
     assert ...

Answer 7

I started out with Johannes Farhenkrug 's answer here and it worked great for me. I needed to mock the requests library because my goal is to isolate my application and not test any 3rd party resources.

Then I read up some more about python's Mock library and I realized that I can replace the MockResponse class, which you might call a 'Test Double' or a 'Fake', with a python Mock class.

The advantage of doing so is access to things like assert_called_with , call_args and so on. No extra libraries are needed. Additional benefits such as 'readability' or 'its more pythonic' are subjective, so they may or may not play a role for you.

Here is my version, updated with using python's Mock instead of a test double:

import json
import requests
from unittest import mock

# defube stubs
AUTH_TOKEN = '{"prop": "value"}'
LIST_OF_WIDGETS = '{"widgets": ["widget1", "widget2"]}'
PURCHASED_WIDGETS = '{"widgets": ["purchased_widget"]}'


# exception class when an unknown URL is mocked
class MockNotSupported(Exception):
  pass


# factory method that cranks out the Mocks
def mock_requests_factory(response_stub: str, status_code: int = 200):
    return mock.Mock(**{
        'json.return_value': json.loads(response_stub),
        'text.return_value': response_stub,
        'status_code': status_code,
        'ok': status_code == 200
    })


# side effect mock function
def mock_requests_post(*args, **kwargs):
    if args[0].endswith('/api/v1/get_auth_token'):
        return mock_requests_factory(AUTH_TOKEN)
    elif args[0].endswith('/api/v1/get_widgets'):
        return mock_requests_factory(LIST_OF_WIDGETS)
    elif args[0].endswith('/api/v1/purchased_widgets'):
        return mock_requests_factory(PURCHASED_WIDGETS)
    
    raise MockNotSupported


# patch requests.post and run tests
with mock.patch('requests.post') as requests_post_mock:
  requests_post_mock.side_effect = mock_requests_post
  response = requests.post('https://myserver/api/v1/get_widgets')
  assert response.ok is True
  assert response.status_code == 200
  assert 'widgets' in response.json()
  
  # now I can also do this
  requests_post_mock.assert_called_with('https://myserver/api/v1/get_widgets')

Repl.it links:

https://repl.it/@abkonsta/Using-unittestMock-for-requestspost#main.py

https://repl.it/@abkonsta/Using-test-double-for-requestspost#main.py

Answer 8

If you want to mock a fake response, another way to do it is to simply instantiate an instance of the base HttpResponse class, like so:

from django.http.response import HttpResponseBase

self.fake_response = HttpResponseBase()

Answer 9

One possible way to work around requests is using the library betamax, it records all requests and after that if you make a request in the same url with the same parameters the betamax will use the recorded request, I have been using it to test web crawler and it save me a lot time.

import os

import requests
from betamax import Betamax
from betamax_serializers import pretty_json


WORKERS_DIR = os.path.dirname(os.path.abspath(__file__))
CASSETTES_DIR = os.path.join(WORKERS_DIR, u'resources', u'cassettes')
MATCH_REQUESTS_ON = [u'method', u'uri', u'path', u'query']

Betamax.register_serializer(pretty_json.PrettyJSONSerializer)
with Betamax.configure() as config:
    config.cassette_library_dir = CASSETTES_DIR
    config.default_cassette_options[u'serialize_with'] = u'prettyjson'
    config.default_cassette_options[u'match_requests_on'] = MATCH_REQUESTS_ON
    config.default_cassette_options[u'preserve_exact_body_bytes'] = True


class WorkerCertidaoTRT2:
    session = requests.session()

    def make_request(self, input_json):
        with Betamax(self.session) as vcr:
            vcr.use_cassette(u'google')
            response = session.get('http://www.google.com')

https://betamax.readthedocs.io/en/latest/

Answer 10

This worked for me, although I haven't done much complicated testing yet.

import json
from requests import Response

class MockResponse(Response):
    def __init__(self,
                 url='http://example.com',
                 headers={'Content-Type':'text/html; charset=UTF-8'},
                 status_code=200,
                 reason = 'Success',
                 _content = 'Some html goes here',
                 json_ = None,
                 encoding='UTF-8'
                 ):
    self.url = url
    self.headers = headers
    if json_ and headers['Content-Type'] == 'application/json':
        self._content = json.dumps(json_).encode(encoding)
    else:
        self._content = _content.encode(encoding)

    self.status_code = status_code
    self.reason = reason
    self.encoding = encoding

Then you can create responses :

mock_response = MockResponse(
    headers={'Content-Type' :'application/json'},
    status_code=401,
    json_={'success': False},
    reason='Unauthorized'
)
mock_response.raise_for_status()

gives

requests.exceptions.HTTPError: 401 Client Error: Unauthorized for url: http://example.com

Answer 11

Can you use requests-mock instead?

Suppose your myview function instead takes a requests.Session object, makes requests with it, and does something to the output:

# mypackage.py
def myview(session):
    res1 = session.get("http://aurl")
    res2 = session.get("http://burl")
    res3 = session.get("http://curl")
    return f"{res1.text}, {res2.text}, {res3.text}"

# test_myview.py
from mypackage import myview
import requests

def test_myview(requests_mock):
    # set up requests
    a_req = requests_mock.get("http://aurl", text="a response")
    b_req = requests_mock.get("http://burl", text="b response")
    c_req = requests_mock.get("http://curl", text="c response")

    # test myview behaviour
    session = requests.Session()
    assert myview(session) == "a response, b response, c response"

    # check that requests weren't called repeatedly
    assert a_req.called_once
    assert b_req.called_once
    assert c_req.called_once
    assert requests_mock.call_count == 3

You can also use requests_mock with frameworks other than Pytest - the documentation is great.

Answer 12

I will add this information since I had a hard time figuring how to mock an async api call.

Here is what I did to mock an async call.

Here is the function I wanted to test

async def get_user_info(headers, payload):
    return await httpx.AsyncClient().post(URI, json=payload, headers=headers)

You still need the MockResponse class

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

    def json(self):
        return self.json_data

You add the MockResponseAsync class

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

    async def getResponse(self):
        return self.response

Here is the test. The important thing here is I create the response before since init function can't be async and the call to getResponse is async so it all checked out.

@pytest.mark.asyncio
@patch('httpx.AsyncClient')
async def test_get_user_info_valid(self, mock_post):
    """test_get_user_info_valid"""
    # Given
    token_bd = "abc"
    username = "bob"
    payload = {
        'USERNAME': username,
        'DBNAME': 'TEST'
    }
    headers = {
        'Authorization': 'Bearer ' + token_bd,
        'Content-Type': 'application/json'
    }
    async_response = MockResponseAsync("", 200)
    mock_post.return_value.post.return_value = async_response.getResponse()

    # When
    await api_bd.get_user_info(headers, payload)

    # Then
    mock_post.return_value.post.assert_called_once_with(
        URI, json=payload, headers=headers)

If you have a better way of doing that tell me but I think it's pretty clean like that.

Answer 13

The simplest way so far:

from unittest import TestCase
from unittest.mock import Mock, patch

from .utils import method_foo


class TestFoo(TestCase):

    @patch.object(utils_requests, "post")  # change to desired method here
    def test_foo(self, mock_requests_post):
        # EXPLANATION: mocked 'post' method above will return some built-in mock, 
        # and its method 'json' will return mock 'mock_data',
        # which got argument 'return_value' with our data to be returned
        mock_data = Mock(return_value=[{"id": 1}, {"id": 2}])
        mock_requests_post.return_value.json = mock_data

        method_foo()

        # TODO: asserts here


"""
Example of method that you can test in utils.py
"""
def method_foo():
    response = requests.post("http://example.com")
    records = response.json()
    for record in records:
        print(record.get("id"))
        # do other stuff here

Answer 14

For those, who don't want to install additional libs for pytest , there is an example. I will duplicate it here with some extension, based on examples above:

import datetime

import requests


class MockResponse:
    def __init__(self, json_data, status_code):
        self.json_data = json_data
        self.status_code = status_code
        self.elapsed = datetime.timedelta(seconds=1)

    # mock json() method always returns a specific testing dictionary
    def json(self):
        return self.json_data


def test_get_json(monkeypatch):
    # Any arguments may be passed and mock_get() will always return our
    # mocked object, which only has the .json() method.
    def mock_get(*args, **kwargs):
        return MockResponse({'mock_key': 'mock_value'}, 418)

    # apply the monkeypatch for requests.get to mock_get
    monkeypatch.setattr(requests, 'get', mock_get)

    # app.get_json, which contains requests.get, uses the monkeypatch
    response = requests.get('https://fakeurl')
    response_json = response.json()

    assert response_json['mock_key'] == 'mock_value'
    assert response.status_code == 418
    assert response.elapsed.total_seconds() == 1


============================= test session starts ==============================
collecting ... collected 1 item

test_so.py::test_get_json PASSED                                          [100%]

============================== 1 passed in 0.07s ===============================

Answer 15

Just a helpful hint to those that are still struggling, converting from urllib or urllib2/urllib3 to requests AND trying to mock a response- I was getting a slightly confusing error when implementing my mock:

with requests.get(path, auth=HTTPBasicAuth('user', 'pass'), verify=False) as url:

AttributeError: __enter__

Well, of course, if I knew anything about how with works (I didn't), I'd know it was a vestigial, unnecessary context (from PEP 343 ). Unnecessary when using the requests library because it does basically the same thing for you under the hood . Just remove the with and use bare requests.get(...) and Bob's your uncle .

Answer 16

For pytest users there is a convinient fixture from https://pypi.org/project/pytest-responsemock/

For example to mock GET to http://some.domain you can:

def test_me(response_mock):

    with response_mock('GET http://some.domain -> 200 :Nice'):
        response = send_request()
        assert result.ok
        assert result.content == b'Nice'

Answer 17

I will demonstrate how to detach your programming logic from the actual external library by swapping the real request with a fake one that returns the same data. In your view if external api call then this process is best

import pytest
from unittest.mock import patch
from django.test import RequestFactory

@patch("path(projectname.appname.filename).requests.post")
def test_mock_response(self, mock_get, rf: RequestFactory):
    mock_get.return_value.ok = Mock(ok=True)
    mock_get.return_value.status_code = 400
    mock_get.return_value.json.return_value = {you can define here dummy response}
    request = rf.post("test/", data=self.payload)
    response = view_name_view(request)

    expected_response = {
        "success": False,
        "status": "unsuccessful",
    }

    assert response.data == expected_response
    assert response.status_code == 400

Answer 18

Using requests_mock is easy to patch any requests

pip install requests-mock

from unittest import TestCase
import requests_mock
from <yourmodule> import <method> (auth)

class TestApi(TestCase):
  @requests_mock.Mocker()
  def test_01_authentication(self, m):
        """Successful authentication using username password"""
        token = 'token'
        m.post(f'http://localhost/auth', json= {'token': token})
        act_token =auth("user", "pass")
        self.assertEqual(act_token, token)

Answer 19

import responses    

@responses.activate
def test_existence_is_false(self):
    responses.add(
        responses.GET,
        url_path,
        json={},
        status=404,
    )
    is_exist = method_send_get_request_to_url_path()
    self.assertFalse(is_exist)