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Responses

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A utility library for mocking out the requests Python library.

Note

Responses requires Python 2.7 or newer, and requests >= 2.0

Installing

pip install responses

Basics

The core of responses comes from registering mock responses:

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"}'

If you attempt to fetch a url which doesn't hit a match, responses will raise a ConnectionError:

import responses
import requests

from requests.exceptions import ConnectionError

@responses.activate
def test_simple():
    with pytest.raises(ConnectionError):
        requests.get('http://twitter.com/api/1/foobar')

Lastly, you can pass an Exception as the body to trigger an error on the request:

import responses
import requests

@responses.activate
def test_simple():
    responses.add(responses.GET, 'http://twitter.com/api/1/foobar',
                  body=Exception('...'))
    with pytest.raises(Exception):
        requests.get('http://twitter.com/api/1/foobar')

Response Parameters

Responses are automatically registered via params on add, but can also be passed directly:

import responses

responses.add(
    responses.Response(
        method='GET',
        url='http://example.com',
    )
)

The following attributes can be passed to a Response mock:

method (str)
The HTTP method (GET, POST, etc).
url (str or compiled regular expression)
The full resource URL.
match_querystring (bool)
Include the query string when matching requests. Enabled by default if the response URL contains a query string, disabled if it doesn't or the URL is a regular expression.
body (str or BufferedReader)
The response body.
json
A Python object representing the JSON response body. Automatically configures the appropriate Content-Type.
status (int)
The HTTP status code.
content_type (content_type)
Defaults to text/plain.
headers (dict)
Response headers.
stream (bool)
Disabled by default. Indicates the response should use the streaming API.
auto_calculate_content_length (bool)
Disabled by default. Automatically calculates the length of a supplied string or JSON body.
match (list)
A list of callbacks to match requests based on request body contents.

Matching Request Parameters

When adding responses for endpoints that are sent request data you can add matchers to ensure your code is sending the right parameters and provide different responses based on the request body contents. Responses provides matchers for JSON and URLencoded request bodies and you can supply your own for other formats.

import responses
import requests
from responses import matchers

@responses.activate
def test_calc_api():
    responses.add(
        responses.POST,
        url='http://calc.com/sum',
        body="4",
        match=[
            matchers.urlencoded_params_matcher({"left": "1", "right": "3"})
        ]
    )
    requests.post("http://calc.com/sum", data={"left": 1, "right": 3})

Matching JSON encoded data can be done with matchers.json_params_matcher(). If your application uses other encodings you can build your own matcher that returns True or False if the request parameters match. Your matcher can expect a request parameter to be provided by responses.

Similarly, you can use the matchers.query_param_matcher function to match against the params request parameter. Note, you must set match_querystring=False

import responses
import requests
from responses import matchers

@responses.activate
def test_calc_api():
    url = "http://example.com/test"
    params = {"hello": "world", "I am": "a big test"}
    responses.add(
        method=responses.GET,
        url=url,
        body="test",
        match=[matchers.query_param_matcher(params)],
        match_querystring=False,
    )

    resp = requests.get(url, params=params)

    constructed_url = r"http://example.com/test?I+am=a+big+test&hello=world"
    assert resp.url == constructed_url
    assert resp.request.url == constructed_url
    assert resp.request.params == params

Dynamic Responses

You can utilize callbacks to provide dynamic responses. The callback must return a tuple of (status, headers, body).

import json

import responses
import requests

@responses.activate
def test_calc_api():

    def request_callback(request):
        payload = json.loads(request.body)
        resp_body = {'value': sum(payload['numbers'])}
        headers = {'request-id': '728d329e-0e86-11e4-a748-0c84dc037c13'}
        return (200, headers, json.dumps(resp_body))

    responses.add_callback(
        responses.POST, 'http://calc.com/sum',
        callback=request_callback,
        content_type='application/json',
    )

    resp = requests.post(
        'http://calc.com/sum',
        json.dumps({'numbers': [1, 2, 3]}),
        headers={'content-type': 'application/json'},
    )

    assert resp.json() == {'value': 6}

    assert len(responses.calls) == 1
    assert responses.calls[0].request.url == 'http://calc.com/sum'
    assert responses.calls[0].response.text == '{"value": 6}'
    assert (
        responses.calls[0].response.headers['request-id'] ==
        '728d329e-0e86-11e4-a748-0c84dc037c13'
    )

You can also pass a compiled regex to add_callback to match multiple urls:

import re, json

from functools import reduce

import responses
import requests

operators = {
  'sum': lambda x, y: x+y,
  'prod': lambda x, y: x*y,
  'pow': lambda x, y: x**y
}

@responses.activate
def test_regex_url():

    def request_callback(request):
        payload = json.loads(request.body)
        operator_name = request.path_url[1:]

        operator = operators[operator_name]

        resp_body = {'value': reduce(operator, payload['numbers'])}
        headers = {'request-id': '728d329e-0e86-11e4-a748-0c84dc037c13'}
        return (200, headers, json.dumps(resp_body))

    responses.add_callback(
        responses.POST,
        re.compile('http://calc.com/(sum|prod|pow|unsupported)'),
        callback=request_callback,
        content_type='application/json',
    )

    resp = requests.post(
        'http://calc.com/prod',
        json.dumps({'numbers': [2, 3, 4]}),
        headers={'content-type': 'application/json'},
    )
    assert resp.json() == {'value': 24}

test_regex_url()

If you want to pass extra keyword arguments to the callback function, for example when reusing a callback function to give a slightly different result, you can use functools.partial:

from functools import partial

...

    def request_callback(request, id=None):
        payload = json.loads(request.body)
        resp_body = {'value': sum(payload['numbers'])}
        headers = {'request-id': id}
        return (200, headers, json.dumps(resp_body))

    responses.add_callback(
        responses.POST, 'http://calc.com/sum',
        callback=partial(request_callback, id='728d329e-0e86-11e4-a748-0c84dc037c13'),
        content_type='application/json',
    )

You can see params passed in the original request in responses.calls[].request.params:

import responses
import requests

@responses.activate
def test_request_params():
    responses.add(
        method=responses.GET,
        url="http://example.com?hello=world",
        body="test",
        match_querystring=False,
    )

    resp = requests.get('http://example.com', params={"hello": "world"})
    assert responses.calls[0].request.params == {"hello": "world"}

Responses as a context manager

import responses
import requests

def test_my_api():
    with responses.RequestsMock() as rsps:
        rsps.add(responses.GET, 'http://twitter.com/api/1/foobar',
                 body='{}', status=200,
                 content_type='application/json')
        resp = requests.get('http://twitter.com/api/1/foobar')

        assert resp.status_code == 200

    # outside the context manager requests will hit the remote server
    resp = requests.get('http://twitter.com/api/1/foobar')
    resp.status_code == 404

Responses as a pytest fixture

@pytest.fixture
def mocked_responses():
    with responses.RequestsMock() as rsps:
        yield rsps

def test_api(mocked_responses):
    mocked_responses.add(
        responses.GET, 'http://twitter.com/api/1/foobar',
        body='{}', status=200,
        content_type='application/json')
    resp = requests.get('http://twitter.com/api/1/foobar')
    assert resp.status_code == 200

Responses inside a unittest setUp()

When run with unittest tests, this can be used to set up some generic class-level responses, that may be complemented by each test

def setUp():
    self.responses = responses.RequestsMock()
    self.responses.start()

    # self.responses.add(...)

    self.addCleanup(self.responses.stop)
    self.addCleanup(self.responses.reset)

def test_api(self):
    self.responses.add(
        responses.GET, 'http://twitter.com/api/1/foobar',
        body='{}', status=200,
        content_type='application/json')
    resp = requests.get('http://twitter.com/api/1/foobar')
    assert resp.status_code == 200

Assertions on declared responses

When used as a context manager, Responses will, by default, raise an assertion error if a url was registered but not accessed. This can be disabled by passing the assert_all_requests_are_fired value:

import responses
import requests

def test_my_api():
    with responses.RequestsMock(assert_all_requests_are_fired=False) as rsps:
        rsps.add(responses.GET, 'http://twitter.com/api/1/foobar',
                 body='{}', status=200,
                 content_type='application/json')

assert_call_count

Assert that the request was called exactly n times.

import responses
import requests

@responses.activate
def test_assert_call_count():
    responses.add(responses.GET, "http://example.com")

    requests.get("http://example.com")
    assert responses.assert_call_count("http://example.com", 1) is True

    requests.get("http://example.com")
    with pytest.raises(AssertionError) as excinfo:
        responses.assert_call_count("http://example.com", 1)
    assert "Expected URL 'http://example.com' to be called 1 times. Called 2 times." in str(excinfo.value)

Multiple Responses

You can also add multiple responses for the same url:

import responses
import requests

@responses.activate
def test_my_api():
    responses.add(responses.GET, 'http://twitter.com/api/1/foobar', status=500)
    responses.add(responses.GET, 'http://twitter.com/api/1/foobar',
                  body='{}', status=200,
                  content_type='application/json')

    resp = requests.get('http://twitter.com/api/1/foobar')
    assert resp.status_code == 500
    resp = requests.get('http://twitter.com/api/1/foobar')
    assert resp.status_code == 200

Using a callback to modify the response

If you use customized processing in requests via subclassing/mixins, or if you have library tools that interact with requests at a low level, you may need to add extended processing to the mocked Response object to fully simulate the environment for your tests. A response_callback can be used, which will be wrapped by the library before being returned to the caller. The callback accepts a response as it's single argument, and is expected to return a single response object.

import responses
import requests

def response_callback(resp):
    resp.callback_processed = True
    return resp

with responses.RequestsMock(response_callback=response_callback) as m:
    m.add(responses.GET, 'http://example.com', body=b'test')
    resp = requests.get('http://example.com')
    assert resp.text == "test"
    assert hasattr(resp, 'callback_processed')
    assert resp.callback_processed is True

Passing through real requests

In some cases you may wish to allow for certain requests to pass through responses and hit a real server. This can be done with the add_passthru methods:

import responses

@responses.activate
def test_my_api():
    responses.add_passthru('https://percy.io')

This will allow any requests matching that prefix, that is otherwise not registered as a mock response, to passthru using the standard behavior.

Regex can be used like:

responses.add_passthru(re.compile('https://percy.io/\\w+'))

Viewing/Modifying registered responses

Registered responses are available as a public method of the RequestMock instance. It is sometimes useful for debugging purposes to view the stack of registered responses which can be accessed via responses.registered().

The replace function allows a previously registered response to be changed. The method signature is identical to add. response s are identified using method and url. Only the first matched response is replaced.

import responses
import requests

@responses.activate
def test_replace():

    responses.add(responses.GET, 'http://example.org', json={'data': 1})
    responses.replace(responses.GET, 'http://example.org', json={'data': 2})

    resp = requests.get('http://example.org')

    assert resp.json() == {'data': 2}

The upsert function allows a previously registered response to be changed like replace. If the response is registered, the upsert function will registered it like add.

remove takes a method and url argument and will remove all matched responses from the registered list.

Finally, reset will reset all registered responses.

Contributing

Responses uses several linting and autoformatting utilities, so it's important that when submitting patches you use the appropriate toolchain:

Clone the repository:

git clone https://github.com/getsentry/responses.git

Create an environment (e.g. with virtualenv):

virtualenv .env && source .env/bin/activate

Configure development requirements:

make develop

Responses uses Pytest for testing. You can run all tests by:

pytest

And run a single test by:

pytest -k '<test_function_name>'

To verify type compliance, run mypy linter:

mypy --config-file=./mypy.ini -p responses

To check code style and reformat it run:

pre-commit run --all-files

Note: on some OS, you have to use pre_commit