Stack-In-A-Box

Testing framework for RESTful APIs

Overview

Stack-In-A-Box is a RESTful API Testing Framework for unit testing applications against the other services

Installing

Installation is simple:

pip install stackinabox

Goals

• Enable Python modules to be unit tested against externals services in particular in an environment entirely controlled by the unittest.
• The service should be started/stopped and configured from the setup/teardown methods of the unittest
• Support both Postive and Negative testing
• Testing should be easy to do:
  • you should not necessarily need to know the ins and outs of each service
  • you should be able to register what you need (f.e authentication, storage) and have it just work
• should be useable on systems like Travis (https://travis-ci.org/), GitHub Actions, etc
• should be light on requirements
  • we do not want to bloat your testing to fit our needs
  • if we have many requirements they could interfere with your requirements
• The code being unit-tested should not be able to tell the difference of whether it is working with Stack-In-A-Box or the real thing
  • there should be nothing special about setting up the test
  • if you don't turn on Stack-In-A-Box then the code should be able to call the real thing
  • caveat: the utility tools (f.e httpretty, requests-mock) will determine the URL for the Stack-In-A-Box Service which will start differently from the URL of the real thing. For example: if the Hello World service was normally run at 'www.helloworld.com/v1', it's Stack-In-A-Box version was registered with Stack-In-A-Box as 'hello/v1', and Stack-In-A-Box was registered using 'localhost', then it's Stack-In-A-Box URL would be 'http://localhost/hello/v1'. The remainder of the URL and any query-string parameters should be the same.

Why not use framework X?

This project initially setup to provide mock-ups of the OpenStack Keystone and Swift APIs. In doing so other frameworks, such as mimic (https://github.com/rackerlabs/mimic) were considered. However, they did not meet the goals set out above. This framework was then built and initially provided the Keystone module that is now part of OpenStack-In-A-Box (https://github.com/TestInABox/openstackinabox). This framework now makes it easy to build services that can be integrated with one of many unit testing frameworks, f.e httpretty, to provide a consistent, reliable unit testing framework that essentially merges the API/Integration-level tests into the more specific unit tests. It does not, however, replace a proper Integration Test as the responses (in terms of time and integration) will likely be different; but it does allow the unit tests to be sufficient to catch the coding errors early on so that you can focus on the real integration problems with the Integration-level tests.

This framework is specifically targetted at running the unit tests, as part of the unit tests, and fully controlled by the unit tests. Projects such as mimic (https://github.com/rackerlabs/mimic) provide a good next-layer of testing if mocked integration level testing is desired; otherwise full integration tests could be utilized.

What's Provided?

Here's what is currently provided:

• An easy to build Service object and end-point registration that is plug-in-play with StackInABox
• A plug-in-play utility set for several testing frameworks so you the developer can choose which fits your needs best
• An example HelloWorld Service to show the basics

Note: The OpenStack-In-A-Box (https://github.com/TestInABox/openstackinabox) provides a more advanced example of building a Stack-In-A-Box Service.

Working with Frameworks

Stack-In-A-Box does not itself provide a socket interception framework. Out-of-the-box it supports the following frameworks:

• HTTPretty (https://github.com/gabrielfalcao/HTTPretty)
• Responses (https://github.com/dropbox/responses)
• Requests-Mock(https://git.openstack.org/cgit/stackforge/requests-mock)

You can use any of them, and you must pull them in via your own test requirements.

Error Codes

StackInABox has some specific error codes to help with diagnosing issues:

• 597 - StackInABox - Base URL is correct, but service is unknown
• 596 - StackInABox - Handling StackInABoxService generated an exception
• 595 - StackInABoxService - Route Not handled

Both of these are extremely easy to use as shown in the following examples:

HTTPretty

httypretty works well with class-based tests.

import unittest

import httpretty
import requests

import stackinabox.util.httpretty
from stackinabox.stack import StackInABox
from stackinabox.services.hello import HelloService


@httpretty.activate
class TestHttpretty(unittest.TestCase):

    def setUp(self):
        super(TestHttpretty, self).setUp()
        StackInABox.register_service(HelloService())

    def tearDown(self):
        super(TestHttpretty, self).tearDown()
        StackInABox.reset_services()

    def test_basic(self):
        stackinabox.util.httpretty.httpretty_registration('localhost')

        res = requests.get('http://localhost/')
        self.assertEqual(res.status_code, 200)
        self.assertEqual(res.text, 'Hello')

There is now also the option of using a decorator:

import unittest

import requests

import stackinabox.util.httpretty.decorator as stack_decorator
from stackinabox.services.hello import HelloService


class TestHttpretty(unittest.TestCase):

    @stack_decorator.stack_activate('localhost', HelloService())
    def test_basic(self):
        res = requests.get('http://localhost/')
        self.assertEqual(res.status_code, 200)
        self.assertEqual(res.text, 'Hello')

Responses

responses works well with function-based tests; however, it does require you use the Python requests library.

import unittest

import responses
import requests

import stackinabox.responses
from stackinabox.stack import StackInABox
from stackinabox.services.hello import HelloService


@responses.activate
def test_basic_responses():
    StackInABox.reset_services()
    StackInABox.register_service(HelloService())
    stackinabox.util.responses.responses_registration('localhost')

    res = requests.get('http://localhost/hello/')
    assert res.status_code == 200
    assert res.text == 'Hello'

There is now also the option of using a decorator:

import unittest

import requests

import stackinabox.util.responses.decorator as stack_decorator
from stackinabox.services.hello import HelloService


@stack_decorator.stack_activate('localhost', HelloService())
def test_basic_responses_with_decorator(self):
    res = requests.get('http://localhost/')
    self.assertEqual(res.status_code, 200)
    self.assertEqual(res.text, 'Hello')

Requests Mock

requests-mock works well with class-based tests, however, it does require that you use the Python requests API. If you use requests-mock directly than you also have to configure requests.session.Session objects and setup your code to use them. However, Stack-In-A-Box makes that unnecessary by providing thread-based session objects that are automatically registered and patching requests to return them automatically. Thus you can either use a Session object directly or just use the nice calls that requests provides and your tests will still just work.

import unittest

import requests

import stackinabox.util.requests_mock
from stackinabox.stack import StackInABox
from stackinabox.services.hello import HelloService

class TestRequestsMock(unittest.TestCase):

    def setUp(self):
        super(TestRequestsMock, self).setUp()
        StackInABox.register_service(HelloService())
        self.session = requests.Session()

    def tearDown(self):
        super(TestRequestsMock, self).tearDown()
        StackInABox.reset_services()
        self.session.close()

    def test_basic_requests_mock(self):
        # Register with existing session object
        stackinabox.util.requests_mock.requests_mock_session_registration(
            'localhost', self.session)

        res = self.session.get('http://localhost/hello/')
        self.assertEqual(res.status_code, 200)
        self.assertEqual(res.text, 'Hello')

    def test_context_requests_mock(self):
        with stackinabox.util.requests_mock.activate():
            # Register without the session object
            stackinabox.util.requests_mock.requests_mock_registration(
                'localhost')

            res = requests.get('http://localhost/hello/')
            self.assertEqual(res.status_code, 200)
            self.assertEqual(res.text, 'Hello')

There is now also the option of using a decorator:

import unittest

import requests

import stackinabox.util.requests_mock.decorator as stack_decorator
from stackinabox.services.hello import HelloService


class TestRequestsMock(unittest.TestCase):

    @stack_decorator.stack_activate('localhost', HelloService())
    def test_basic(self):
        res = requests.get('http://localhost/')
        self.assertEqual(res.status_code, 200)
        self.assertEqual(res.text, 'Hello')

Enjoy!

Please now go and enjoy better testing.