hulk

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Table of Contents

• 1   Introduction
• 2   Installation
• 3   Usage
• 4   Tests
• 5   Change Log
• 6   Dev Notes
• 7   Design Decisions
• 8   Roadmap

1   Introduction

hulk is a big dumb proxy server for testing service-heavy applications. Designed for use with requests>=2.0.0. hulk caches request data behind the scenes for later use in application testing. Note that hulk is not a mocking library, it caches actual service calls for later use. We've found that when we have dozens of large API requests to internal and external sources (and in every imaginable format), we were spending too much time trying to mock out the data, and then the mocks were often incomplete and brittle, or that data applied under one context, but would need another mock for a slightly different context.

Instead of writing mocks until the end of time, we wrote hulk. Hulk does the heavy lifting so you can get busy writing tests.

NOTE: hulk is only currently compatible with requests>=2.0.0.

1.1   Author

Aaron Fay

1.2   Status

Development

1.3   Documentation

See Usage.

2   Installation

$ pip install hulk

OR

Pull down this repository or use the Vagrantfile provided in the repo.

3   Usage

3.1   Vagrant

You're going to need Vagrant if you want to use the included Vagrantfile.

Quickstart:

$ vagrant up
$ vagrant ssh

The login should give you something that looks like this:

Welcome to Ubuntu 12.04.1 LTS (GNU/Linux 3.2.0-32-generic x86_64)

 * Documentation:  https://help.ubuntu.com/

  System information as of Tue Jun 10 14:23:19 BRT 2014

  System load:  0.07              Processes:           71
  Usage of /:   13.0% of 7.87GB   Users logged in:     0
  Memory usage: 1%                IP address for eth0: 192.168.88.15
  Swap usage:   0%                IP address for eth1: 192.168.0.166

  Graph this data and manage this system at https://landscape.canonical.com/

Last login: Wed Jun  4 18:42:19 2014 from 192.168.88.2

To get started with hulk, run:
    $ workon hulk
    $ hulk -h

Follow the instructions (the last couple lines) to get started. Note that you'll want the second IP address listed above to set as your HTTP_PROXY later.

3.2   Hulk command line reference

(hulk)vagrant@vagrant-ubuntu:~$ hulk -h
Big dumb proxy server for testing service-heavy applications.

Usage:
  hulk [--dataset=testing] [--load-origin] [--base-folder] [--debug]
  hulk (--help | -h)

Options:
  --dataset=testing   The set of cached data to use [default: testing]
  --load-origin       Use this flag to populate new datasets
  --debug             Run hulk with debugging info
  --help -h           Show this screen.

The first time you run hulk you'll want to use the --load-origin flag to have hulk load the original service call data and cache it to disk.

$ hulk --load-origin

Each request gets a hash assigned to it and is saved to the local file system in the original format under the dataset folder you've specified. Subsequent requests will use the cached file.

3.3   Datasets

datasets allow you to have different sets of data for different scenarios, possible test suites or even different applications. To get started with a new dataset, run:

$ hulk --load-origin --dataset=my-new-dataset

The new dataset my-new-dataset will be created in the datasets folder. To run hulk with the dataset in the future, just run:

$ hulk --dataset=my-new-dataset

3.3.1   HULK_DATASET_BASE_DIR

By default, hulk creates a datasets folder relative to the hulk installation. If you would like to change the location where the datasets get stored, you can set the HULK_DATASET_BASE_DIR environment variable. This should be an absolute path to where you want the datasets to be saved, for example:

$ export HULK_DATASET_BASE_DIR=/tmp/datasets

3.4   Using HTTP_PROXY

Following the tradition of it's predecessors, the fantastic requests library honors the HTTP_PROXY environment variable and will use the value specified as the proxy server for all requests. For example, if you run your application like so:

$ export HTTP_PROXY=http://192.168.0.166:6000 && run_my_application

...you should be able to navigate your app and watch the hulk server load and serve your service data.

There are a couple important things to note with the above environment variable:

• you must specify the protocol (eg http://)
• hulk runs on port 6000 by default

3.5   Using the datasets without hulk

There is also a decorator available to patch requests so you can utilize datasets in your test suite without running hulk: hulk.monkey.with_dataset.

This decorator can be used on a per-method or per-class basis. For example:

from hulk.monkey import with_dataset
import unittest
import requests


@with_dataset('my-ticket-1234')
class SuperTestCase(unittest.TestCase)
    def setUp(self):
        pass

    def test_should_pass(self):
        """This service request will actually look for the data in your
        `datasets/my-ticket-1234/my-service.com/...` folder. If the folder
        or file for this specific response doesn't exist, you'll get a 404
        response code.
        """
        response = requests.get('http://my-service.com/some-data')
        self.assertEqual(response.status_code, 200)

Note: The class- and method-level decorators cannot be currently used together in a stack-like fashion, meaning that if you use a class-level decorator, then use a method-level decorator, with_dataset will not fall back to the class-level decorator. Currently it is recommended to use the decorator at the class level.

4   Tests

To run the tests:

$ nosetests --with-spec --spec-color --with-coverage --cover-package=hulk

5   Change Log

• 0.2.1: fix bug in with_dataset to ensure requests is patched, check requests version
• 0.2.0: adds with_dataset decorator, class decorator support, and updated docs.
• 0.1.0: initial version

6   Dev Notes

7   Design Decisions

8   Roadmap

• compatibility with requests < 2.0.0
• load/save datasets in S3
• compatibility with urllib/other http libs?
• database support

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