Unit testing a python app that uses the requests library

Unit testing a python app that uses the requests library

It is in fact a little strange that the library has a blank page about end-user unit testing, while targeting user-friendliness and ease of use. Theres however an easy-to-use library by Dropbox, unsurprisingly called responses. Here is its intro post. It says theyve failed to employ httpretty, while stating no reason of the fail, and written a library with similar API.

import unittest

import requests
import responses


class TestCase(unittest.TestCase):

  @responses.activate  
  def testExample(self):
    responses.add(**{
      method         : responses.GET,
      url            : http://example.com/api/123,
      body           : {error: reason},
      status         : 404,
      content_type   : application/json,
      adding_headers : {X-Foo: Bar}
    })

    response = requests.get(http://example.com/api/123)

    self.assertEqual({error: reason}, response.json())
    self.assertEqual(404, response.status_code)

If you use specifically requests try httmock. Its wonderfully simple and elegant:

from httmock import urlmatch, HTTMock
import requests

# define matcher:
@urlmatch(netloc=r(.*.)?google.com$)
def google_mock(url, request):
    return Feeling lucky, punk?

# open context to patch
with HTTMock(google_mock):
    # call requests
    r = requests.get(http://google.com/)
print r.content  # Feeling lucky, punk?

If you want something more generic (e.g. to mock any library making http calls) go for httpretty.

Almost as elegant:

import requests
import httpretty

@httpretty.activate
def test_one():
    # define your patch:
    httpretty.register_uri(httpretty.GET, http://yipit.com/,
                        body=Find the best daily deals)
    # use!
    response = requests.get(http://yipit.com)
    assert response.text == Find the best daily deals

HTTPretty is far more feature-rich – it offers also mocking status code, streaming responses, rotating responses, dynamic responses (with a callback).

Unit testing a python app that uses the requests library

You could use a mocking library such as Mocker to intercept the calls to the requests library and return specified results.

As a very simple example, consider this class which uses the requests library:

class MyReq(object):
    def doSomething(self):
        r = requests.get(https://api.github.com, auth=(user, pass))
        return r.headers[content-type]

Heres a unit test that intercepts the call to requests.get and returns a specified result for testing:

import unittest
import requests
import myreq

from mocker import Mocker, MockerTestCase

class MyReqTests(MockerTestCase):
    def testSomething(self):
        # Create a mock result for the requests.get call
        result = self.mocker.mock()
        result.headers
        self.mocker.result({content-type: mytest/pass})

        # Use mocker to intercept the call to requests.get
        myget = self.mocker.replace(requests.get)
        myget(https://api.github.com, auth=(user, pass))
        self.mocker.result(result)

        self.mocker.replay()

        # Now execute my code
        r = myreq.MyReq()
        v = r.doSomething()

        # and verify the results
        self.assertEqual(v, mytest/pass)
        self.mocker.verify()

if __name__ == __main__:
    unittest.main()

When I run this unit test I get the following result:

.
----------------------------------------------------------------------
Ran 1 test in 0.004s

OK