python-httpretty/docs/source/introduction.rst

.. _introduction:

`Github <https://github.com/gabrielfalcao/HTTPretty>`_


What is HTTPretty ?
###################

.. highlight:: python

Once upon a time a python developer wanted to use a RESTful api,
everything was fine but until the day he needed to test the code that
hits the RESTful API: what if the API server is down? What if its
content has changed ?

Don't worry, HTTPretty is here for you:

::

  import logging
  import requests
  import httpretty

  from sure import expect

  logging.getLogger('httpretty.core').setLevel(logging.DEBUG)

  @httpretty.activate(allow_net_connect=False)
  def test_yipit_api_returning_deals():
      httpretty.register_uri(httpretty.GET, "http://api.yipit.com/v1/deals/",
                             body='[{"title": "Test Deal"}]',
                             content_type="application/json")

      response = requests.get('http://api.yipit.com/v1/deals/')

      expect(response.json()).to.equal([{"title": "Test Deal"}])


A more technical description
============================

HTTPretty is a python library that swaps the modules :py:mod:`socket`
and :py:mod:`ssl` with fake implementations that intercept HTTP
requests at the level of a TCP connection.

It is inspired on Ruby's `FakeWeb <http://fakeweb.rubyforge.org/>`_.

If you come from the Ruby programming language this would probably sound familiar :smiley:

Installing
==========

Installing httpretty is as easy as:

.. highlight:: bash

::

   pip install httpretty


Demo
####

expecting a simple response body
================================


.. code:: python

   import requests
   import httpretty

   def test_one():
       httpretty.enable(verbose=True, allow_net_connect=False)  # enable HTTPretty so that it will monkey patch the socket module
       httpretty.register_uri(httpretty.GET, "http://yipit.com/",
                              body="Find the best daily deals")

       response = requests.get('http://yipit.com')

       assert response.text == "Find the best daily deals"

       httpretty.disable()  # disable afterwards, so that you will have no problems in code that uses that socket module
       httpretty.reset()    # reset HTTPretty state (clean up registered urls and request history)


making assertions in a callback that generates the response body
================================================================

.. code:: python

   import requests
   import json
   import httpretty

   @httpretty.activate
   def test_with_callback_response():
     def request_callback(request, uri, response_headers):
         content_type = request.headers.get('Content-Type')
         assert request.body == '{"nothing": "here"}', 'unexpected body: {}'.format(request.body)
         assert content_type == 'application/json', 'expected application/json but received Content-Type: {}'.format(content_type)
         return [200, response_headers, json.dumps({"hello": "world"})]

     httpretty.register_uri(
         httpretty.POST, "https://httpretty.example.com/api",
         body=request_callback)

     response = requests.post('https://httpretty.example.com/api', headers={'Content-Type': 'application/json'}, data='{"nothing": "here"}')

     expect(response.json()).to.equal({"hello": "world"})


Link headers
============


 Tests link headers by using the `adding_headers` parameter.


 .. code:: python

    import requests
    from sure import expect
    import httpretty


    @httpretty.activate
    def test_link_response():
        first_url = "http://foo-api.com/data"
        second_url = "http://foo-api.com/data?page=2"
        link_str = "<%s>; rel='next'" % second_url

        httpretty.register_uri(
            httpretty.GET,
            first_url,
            body='{"success": true}',
            status=200,
            content_type="text/json",
            adding_headers={"Link": link_str},
        )
        httpretty.register_uri(
            httpretty.GET,
            second_url,
            body='{"success": false}',
            status=500,
            content_type="text/json",
        )
        # Performs a request to `first_url` followed by some testing
        response = requests.get(first_url)
        expect(response.json()).to.equal({"success": True})
        expect(response.status_code).to.equal(200)
        next_url = response.links["next"]["url"]
        expect(next_url).to.equal(second_url)

        # Follow the next URL and perform some testing.
        response2 = requests.get(next_url)
        expect(response2.json()).to.equal({"success": False})
        expect(response2.status_code).to.equal(500)


Motivation
##########

When building systems that access external resources such as RESTful
webservices, XMLRPC or even simple HTTP requests, we stumble in the
problem:

    *"I'm gonna need to mock all those requests"*

It can be a bit of a hassle to use something like
:py:class:`mock.Mock` to stub the requests, this can work well for
low-level unit tests but when writing functional or integration tests
we should be able to allow the http calls to go through the TCP socket
module.

HTTPretty `monkey patches
<http://en.wikipedia.org/wiki/Monkey_patch>`_ Python's
:py:mod:`socket` core module with a fake version of the module.

Because HTTPretty implements a fake the modules :py:mod:`socket` and
:py:mod:`ssl` you can use write tests to code against any HTTP library
that use those modules.