# Puffing Billy [![Gem Version](https://badge.fury.io/rb/puffing-billy.svg)](https://badge.fury.io/rb/puffing-billy) [![Build Status](https://travis-ci.org/oesmith/puffing-billy.svg?branch=master)](https://travis-ci.org/oesmith/puffing-billy)

A rewriting web proxy for testing interactions between your browser and
external sites. Works with ruby + rspec.

Puffing Billy is like [webmock](https://github.com/bblimke/webmock) or
[VCR](https://github.com/vcr/vcr), but for your browser.

![](http://upload.wikimedia.org/wikipedia/commons/0/01/Puffing_Billy_1862.jpg)

## Overview

Billy spawns an EventMachine-based proxy server, which it uses to intercept
requests sent by your browser. It has a simple API for configuring which
requests need stubbing and what they should return.

Billy lets you test against known, repeatable data.  It also allows you to
test for failure cases.  Does your twitter (or facebook/google/etc)
integration degrade gracefully when the API starts returning 500s?  Well now
you can test it!

```ruby
it 'should stub google' do
  proxy.stub('http://www.google.com/').and_return(:text => "I'm not Google!")
  visit 'http://www.google.com/'
  expect(page).to have_content("I'm not Google!")
end
```

You can also record HTTP interactions and replay them later. See
[caching](#caching) below.

## Installation

Add this line to your application's Gemfile:

    gem 'puffing-billy'

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install puffing-billy

## RSpec Usage

### Setup for Capybara

In your `rails_helper.rb`:

```ruby
require 'billy/capybara/rspec'

# select a driver for your chosen browser environment
Capybara.javascript_driver = :selenium_billy # Uses Firefox
# Capybara.javascript_driver = :selenium_chrome_billy
# Capybara.javascript_driver = :webkit_billy
# Capybara.javascript_driver = :poltergeist_billy
```

> __Note__: `:poltergeist_billy` doesn't support proxying any localhosts, so you must use
`:webkit_billy` for headless specs when using puffing-billy for other local rack apps.
See [this phantomjs issue](https://github.com/ariya/phantomjs/issues/11342) for any updates.

### Setup for Watir

In your `rails_helper.rb`:

```ruby
require 'billy/watir/rspec'

# select a driver for your chosen browser environment
@browser = Billy::Browsers::Watir.new :firefox
# @browser = Billy::Browsers::Watir.new = :chrome
# @browser = Billy::Browsers::Watir.new = :phantomjs
```

### In your tests (Capybara/Watir)

```ruby
# Stub and return text, json, jsonp (or anything else)
proxy.stub('http://example.com/text/').and_return(:text => 'Foobar')
proxy.stub('http://example.com/json/').and_return(:json => { :foo => 'bar' })
proxy.stub('http://example.com/jsonp/').and_return(:jsonp => { :foo => 'bar' })
proxy.stub('http://example.com/headers/').and_return({
  :headers => { 'Access-Control-Allow-Origin' => '*' },
  :json    => { :foo => 'bar' }
})
proxy.stub('http://example.com/wtf/').and_return(:body => 'WTF!?', :content_type => 'text/wtf')

# Stub redirections and other return codes
proxy.stub('http://example.com/redirect/').and_return(:redirect_to => 'http://example.com/other')
proxy.stub('http://example.com/missing/').and_return(:code => 404, :body => 'Not found')

# Even stub HTTPS!
proxy.stub('https://example.com:443/secure/').and_return(:text => 'secrets!!1!')

# Pass a Proc (or Proc-style object) to create dynamic responses.
#
# The proc will be called with the following arguments:
#   params:  Query string parameters hash, CGI::escape-style
#   headers: Headers hash
#   body:    Request body string
#   url:     The actual URL which was requested
#   method:  The HTTP verb which was requested
proxy.stub('https://example.com/proc/').and_return(Proc.new { |params, headers, body, url, method|
  {
    :code => 200,
    :text => "Hello, #{params['name'][0]}"
  }
})

# You can also use Puffing Billy to intercept requests and responses. Just pass
# a Proc and use the pass_request method. You can manipulate the request
# (headers, URL, HTTP method, etc) and also the response from the upstream
# server. The scope of the delivered callable is the user scope where
# it was defined.
proxy.stub('http://example.com/').and_return(Proc.new { |*args|
  response = Billy.pass_request(*args)
  response[:headers]['Content-Type'] = 'text/plain'
  response[:body] = 'Hello World!'
  response[:code] = 200
  response
})

# Stub out a POST. Don't forget to allow a CORS request and set the method to 'post'
proxy.stub('http://example.com/api', :method => 'post').and_return(
  :headers => { 'Access-Control-Allow-Origin' => '*' },
  :code => 201
)

# Stub out an OPTIONS request. Set the headers to the values you require.
proxy.stub('http://example.com/api', :method => :options).and_return(
  :headers => {
    'Access-Control-Allow-Methods' => 'GET, PATCH, POST, PUT, OPTIONS',
    'Access-Control-Allow-Headers' => 'X-Requested-With, X-Prototype-Version, Content-Type',
    'Access-Control-Allow-Origin'  => '*'
  },
  :code => 200
)
```

Stubs are reset between tests.  Any requests that are not stubbed will be
proxied to the remote server.

If for any reason you'd need to reset stubs manually you can do it in two ways:

```ruby
# reset a single stub
example_stub = proxy.stub('http://example.com/text/').and_return(:text => 'Foobar')
proxy.unstub example_stub

# reset all stubs
proxy.reset
```

## Cucumber Usage

An example feature:

```
Feature: Stubbing via billy

  @javascript @billy
  Scenario: Test billy
    And a stub for google
```

### Capybara

In your `features/support/env.rb`:

```ruby
require 'billy/capybara/cucumber'

After do
  Capybara.use_default_driver
end
```

And in steps:

```ruby
Before('@billy') do
  Capybara.current_driver = :poltergeist_billy
end

And /^a stub for google$/ do
  proxy.stub('http://www.google.com/').and_return(:text => "I'm not Google!")
  visit 'http://www.google.com/'
  expect(page).to have_content("I'm not Google!")
end
```

It's good practice to reset the driver after each scenario, so having an
`@billy` tag switches the drivers on for a given scenario. Also note that
stubs are reset after each step, so any usage of a stub should be in the
same step that it was created in.

### Watir

In your `features/support/env.rb`:

```ruby
require 'billy/watir/cucumber'

After do
  @browser.close
end
```

And in steps:

```ruby
Before('@billy') do
  @browser = Billy::Browsers::Watir.new :firefox
end

And /^a stub for google$/ do
  proxy.stub('http://www.google.com/').and_return(:text => "I'm not Google!")
  @browser.goto 'http://www.google.com/'
  expect(@browser.text).to eq("I'm not Google!")
end
```

## Minitest Usage

Please see [this link](https://gist.github.com/sauy7/1b081266dd453a1b737b) for
details and report back to [Issue #49](https://github.com/oesmith/puffing-billy/issues/49)
if you get it fully working.

## Caching

Requests routed through the external proxy are cached.

By default, all requests to localhost or 127.0.0.1 will not be cached. If
you're running your test server with a different hostname, you'll need to
add that host to puffing-billy's whitelist.

In your `rails_helper.rb`:

```ruby
Billy.configure do |c|
  c.whitelist = ['test.host', 'localhost', '127.0.0.1']
end
```

If you would like to cache other local rack apps, you must whitelist only the
specific port for the application that is executing tests.  If you are using
[Capybara](https://github.com/jnicklas/capybara), this can be accomplished by
adding this in your `rails_helper.rb`:

```ruby
server = Capybara.current_session.server
Billy.config.whitelist = ["#{server.host}:#{server.port}"]
```

If you want to use puffing-billy like you would [VCR](https://github.com/vcr/vcr)
you can turn on cache persistence. This way you don't have to manually mock out
everything as requests are automatically recorded and played back. With cache
persistence you can take tests completely offline.

```ruby
Billy.configure do |c|
  c.cache = true
  c.cache_request_headers = false
  c.ignore_params = ["http://www.google-analytics.com/__utm.gif",
                     "https://r.twimg.com/jot",
                     "http://p.twitter.com/t.gif",
                     "http://p.twitter.com/f.gif",
                     "http://www.facebook.com/plugins/like.php",
                     "https://www.facebook.com/dialog/oauth",
                     "http://cdn.api.twitter.com/1/urls/count.json"]
  c.path_blacklist = []
  c.merge_cached_responses_whitelist = []
  c.persist_cache = true
  c.ignore_cache_port = true # defaults to true
  c.non_successful_cache_disabled = false
  c.non_successful_error_level = :warn
  c.non_whitelisted_requests_disabled = false
  c.cache_path = 'spec/req_cache/'
  c.certs_path = 'spec/req_certs/'
  c.proxy_host = 'example.com' # defaults to localhost
  c.proxy_port = 12345 # defaults to random
  c.proxied_request_host = nil
  c.proxied_request_port = 80
  c.record_requests = true # defaults to false
  c.cache_request_body_methods = ['post', 'patch', 'put'] # defaults to ['post']
end
```

The cache works with all types of requests and will distinguish between
different POST requests to the same URL.

`c.cache_request_headers` is used to store the outgoing request headers in the cache.
It is also saved to yml if `persist_cache` is enabled.  This additional information
is useful for debugging (for example: viewing the referer of the request).

`c.ignore_params` is used to ignore parameters of certain requests when
caching. You should mostly use this for analytics and various social buttons as
they use cache avoidance techniques, but return practically the same response
that most often does not affect your test results.

`c.allow_params` is used to allow parameters of certain requests when caching. This is best used when a site
has a large number of analytics and social buttons. `c.allow_params` is the opposite of `c.ignore_params`,
a whitelist to a blacklist. In order to toggle between using one or the other, use `c.use_ignore_params`.

`c.strip_query_params` is used to strip query parameters when you stub some requests
with query parameters. Default value is true. For example, `proxy.stub('http://myapi.com/user/?country=FOO')`
is considered the same as: `proxy.stub('http://myapi.com/user/?anything=FOO')` and
generally the same as: `proxy.stub('http://myapi.com/user/')`. When you need to distinguish between all these requests,
you may set this config value to false.

`c.dynamic_jsonp` is used to rewrite the body of JSONP responses based on the
callback parameter. For example, if a request to `http://example.com/foo?callback=bar`
returns `bar({"some": "json"});` and is recorded, then a later request to
`http://example.com/foo?callback=baz` will be a cache hit and respond with
`baz({"some": "json"});` This is useful because most JSONP implementations
base the callback name off of a timestamp or something else dynamic.

`c.dynamic_jsonp_keys` is used to configure which parameters to ignore when
using `c.dynamic_jsonp`. This is helpful when JSONP APIs use cache-busting
parameters. For example, if you want `http://example.com/foo?callback=bar&id=1&cache_bust=12345` and `http://example.com/foo?callback=baz&id=1&cache_bust=98765` to be cache hits for each other, you would set `c.dynamic_jsonp_keys = ['callback', 'cache_bust']` to ignore both params. Note
that in this example the `id` param would still be considered important.

`c.dynamic_jsonp_callback_name` is used to configure the name of the JSONP callback
parameter. The default is `callback`.

`c.path_blacklist = []` is used to always cache specific paths on any hostnames,
including whitelisted ones.  This is useful if your AUT has routes that get data
from external services, such as `/api` where the ajax request is a local URL but
the actual data is coming from a different application that you want to cache.

`c.merge_cached_responses_whitelist = []` is used to group together the cached
responses for specific uri regexes that match any part of the url. This is useful
for ensuring that any kind of analytics and various social buttons that have
slightly different urls each time can be recorded once and reused nicely. Note
that the request body is ignored for requests that contain a body.

`c.ignore_cache_port` is used to strip the port from the URL if it exists.  This
is useful when caching local paths (via `path_blacklist`) or other local rack apps
that are running on random ports.

`c.non_successful_cache_disabled` is used to not cache responses without 200-series
or 304 status codes.  This prevents unauthorized or internal server errors from
being cached and used for future test runs.

`c.non_successful_error_level` is used to log when non-successful responses are
received.  By default, it just writes to the log file, but when set to `:error`
it throws an error with the URL and status code received for easier debugging.

`c.non_whitelisted_requests_disabled` is used to disable hitting new URLs when
no cache file exists.  Only whitelisted URLs (on non-blacklisted paths) are
allowed, all others will throw an error with the URL attempted to be accessed.
This is useful for debugging issues in isolated environments (ie.
continuous integration).

`c.cache_path` can be used to locate the cache directory to a different place
other than `system temp directory/puffing-billy`.

`c.certs_path` can be used to locate the directory for dynamically generated
SSL certificates to a different place other than `system temp
directory/puffing-billy/certs`.

`c.proxy_host` and `c.proxy_port` are used for the Billy proxy itself which runs locally.

`c.proxied_request_host` and `c.proxied_request_port` are used if an internal proxy
server is required to access the internet.  Most common in larger companies.

`c.record_requests` can be used to record all requests that puffing billy proxied.
This can be useful for debugging purposes, for instance if you are unsure why
your stubbed requests are not being successfully proxied.

Example usage:

```ruby
require 'table_print' # Add this dependency to your gemfile

Billy.configure do |c|
  c.record_requests = true
end

RSpec.configure do |config|
  config.prepend_after(:example, type: :feature) do
    puts "Requests received via Puffing Billy Proxy:"

    puts TablePrint::Printer.table_print(Billy.proxy.requests, [
      :status,
      :handler,
      :method,
      { url: { width: 100 } },
      :headers,
      :body
    ])
  end
end
```

This will generate a human readable list of all requests after each test run:

```
Requests received via Puffing Billy Proxy:
STATUS   | HANDLER | METHOD  | URL                                     | HEADERS                        | BODY
---------|---------|---------|-----------------------------------------|--------------------------------|-----
complete | proxy   | GET     | http://127.0.0.1:56692/                 | {"Accept"=>"text/html,appli... |
complete | proxy   | GET     | http://127.0.0.1:56692/assets/appl...   | {"Accept"=>"text/css,*/*;q=... |
complete | proxy   | GET     | http://127.0.0.1:56692/assets/app...    | {"Accept"=>"*/*", "Referer"... |
complete | proxy   | GET     | http://127.0.0.1:56692/javascript/index | {"Accept"=>"text/html,appli... |
complete | stubs   | OPTIONS | https://api.github.com:443/             | {"Access-Control-Request-Me... |
complete | stubs   | GET     | https://api.github.com:443/             | {"Accept"=>"*/*", "Referer"... |
inflight |         | GET     | http://127.0.0.1:56692/example          | {"Referer"=>"http://127.0.0... |
.

Finished in 1.98 seconds (files took 2.11 seconds to load)
1 example, 0 failures
```

The handler column indicates how Puffing Billy handled your request:

- proxy: This request was successfully routed to the original target
- stubs: This was handled via a stub
- error: This request was not handled by a stub, and was not successfully handled
- cache: This response was handled by a previous cache

If your `status` is set to in_flight this request has not yet been handled fully. Either puffing billy crashed
internally on this request, or your test ended before it could complete successfully.

`c.cache_request_body_methods` is used to specify HTTP methods of requests that you would like to cache separately based on the contents of the request body. The default is ['post'].

`c.after_cache_handles_request` is used to configure a callback that can operate on the response after it has been retrieved from the cache but before it is returned. The callback receives the request and response as arguments, with a request object like: `{ method: method, url: url, headers: headers, body: body }`. An example usage would be manipulating the Access-Control-Allow-Origin header so that your test server doesn't always have to run on the same port in order to accept cached responses to CORS requests:

`c.use_ignore_params` is used to choose whether to use the ignore_params blacklist or the allow_params whitelist. Set to `true` to use `c.ignore_params`,
`false` to use `c.allow_params`

```
Billy.configure do |c|
  ...
  fix_cors_header = proc do |_request, response|
    allowed_origins = response[:headers]['Access-Control-Allow-Origin']
    if allowed_origins.present?
      localhost_port_pattern = %r{(?<=http://127\.0\.0\.1:)(\d+)}
      allowed_origins.sub!(
        localhost_port_pattern, Capybara.current_session.server.port.to_s
      )
    end
  end
  c.after_cache_handles_request = fix_cors_header
  ...
end
```

`c.cache_simulates_network_delays` is used to add some delay before cache returns response. When set to `true`, cached requests will wait from configured delay time before responding. This allows to catch various race conditions in asynchronous front-end requests. The default is `false`.

`c.cache_simulates_network_delay_time` is used to configure time (in seconds) to wait until responding from cache. The default is `0.1`.

### Cache Scopes

If you need to cache different responses to the same HTTP request, you can use
cache scoping.

For example, an index page may return zero or more items in a list, with or
without pagination, depending on the number of entries in a database.

There are a few different ways to use cache scopes:

```ruby
# If you do nothing, it uses the default cache scope:
it 'defaults to nil scope' do
  expect(proxy.cache.scope).to be_nil
end

# You can change context indefinitely to a specific cache scope:
context 'with a cache scope' do
  before do
    proxy.cache.scope_to "my_cache"
  end

  # Remember to set the cache scope back to the default in an after block
  # within the context it is used, and/or at the global rails_helper level!
  after do
    proxy.cache.use_default_scope
  end

  it 'uses the cache scope' do
    expect(proxy.cache.scope).to eq("my_cache")
  end

  it 'can be reset to the default scope' do
    proxy.cache.use_default_scope
    expect(proxy.cache.scope).to be_nil
  end

  # Or you can run a block within the context of a cache scope:
  # Note: When using scope blocks, be sure that both the action that triggers a
  #       request and the assertion that a response has been received are within the block
  it 'can execute a block against a named cache' do
    expect(proxy.cache.scope).to eq("my_cache")
    proxy.cache.with_scope "another_cache" do
      expect(proxy.cache.scope).to eq "another_cache"
    end
    # It
    expect(proxy.cache.scope).to eq("my_cache")
  end
end
```

If you use named caches it is highly recommend that you use a global
hook to set the cache back to the default before or after each test.

In Rspec:

```ruby
RSpec.configure do |config|
  config.before :each { proxy.cache.use_default_scope }
end
```

## Separate Cache Directory for Each Test (in Cucumber)

If you want the cache for each test to be independent, i.e. have it's own directory where the cache files are stored, you can use a Before tag like so:

```rb
Before('@javascript') do |scenario, block|
  Billy.configure do |c|
    feature_name = scenario.feature.name.underscore
    scenario_name = scenario.name.underscore
    c.cache_path = "features/support/fixtures/req_cache/#{feature_name}/#{scenario_name}/"
    Dir.mkdir_p(Billy.config.cache_path) unless File.exist?(Billy.config.cache_path)
  end
end
```

## Stub requests recording

If you want to record requests to stubbed URIs, set the following configuration option:

```ruby
Billy.configure do |c|
  c.record_stub_requests = true
end
```

Example usage:

```ruby
it 'should intercept a GET request' do
  stub = proxy.stub('http://example.com/')
  visit 'http://example.com/'
  expect(stub.has_requests?).to be true
  expect(stub.requests).not_to be_empty
end
```

## Proxy timeouts

By default, the Puffing Billy proxy will use the EventMachine:HttpRequest timeouts of 5 seconds
for connect and 10 seconds for inactivity when talking to downstream servers.

These can be configured as follows:

```ruby
Billy.configure do |c|
  c.proxied_request_connect_timeout = 20
  c.proxied_request_inactivity_timeout = 20
end
```

## Customising the javascript driver

If you use a customised Capybara driver, remember to set the proxy address
and tell it to ignore SSL certificate warnings. See
[lib/billy.rb](https://github.com/oesmith/puffing-billy/blob/master/lib/billy.rb)
to see how Billy's default drivers are configured.

## Working with VCR and Webmock
If you use VCR and Webmock elsewhere in your specs, you may need to disable them
for your specs utilizing Puffing Billy. To do so, you can configure your `rails_helper.rb`
as shown below:

```ruby
RSpec.configure do |config|
  config.around(:each, type: :feature) do |example|
    WebMock.allow_net_connect!
    VCR.turned_off { example.run }
    WebMock.disable_net_connect!
  end
end
```

As an alternative if you're using VCR, you can ignore requests coming from the browser.
One way of doing that is by adding to your `rails_helper.rb` the excerpt below:

```ruby
VCR.configure do |config|
  config.ignore_request do |request|
    request.headers.include?('Referer')
  end
end
```

Note that this approach may cause unexpected behavior if your backend sends the Referer HTTP header (which is unlikely).

### Raising errors from stubs

By default PuffingBilly suppress errors from stub-blocks.
To make it raise errors instead, add this test initializers:

```ruby
EM.error_handler { |e| raise e }
```

## SSL usage

Unfortunately we cannot setup the runtime certificate authority on your browser
at time of configuring the Capybara driver.  So you need to take care of this
step yourself as a prepartion. A good point would be directly after configuring
this gem.

### Google Chrome Headless example

Google Chrome/Chromium is capable to run as a test browser with the new
headless mode which is not able to handle the deprecated
`--ignore-certificate-errors` flag. But the headless mode is capable of
handling the user PKI certificate store.  So you just need to import the
runtime Puffing Billy certificate authority on your system store, or generate a
new store for your current session. The following examples demonstrates the
former variant:

```ruby
# Install the fabulous `os` gem first
# See: https://rubygems.org/gems/os
# gem install os
#
# --

# Overwrite the local home directory for chrome. We use this
# to setup a custom SSL certificate store.
ENV['HOME'] = "#{Dir.tmpdir}/chrome-home-#{Time.now.to_i}"

# Clear and recreate the Chrome home directory.
FileUtils.rm_rf(ENV['HOME'])
FileUtils.mkdir_p(ENV['HOME'])

# Setup a new pki certificate database for Chrome
if OS.linux?
  system <<~SCRIPT
    cd "#{ENV['HOME']}"
    curl -s -k -o "cacert-root.crt" "http://www.cacert.org/certs/root.crt"
    curl -s -k -o "cacert-class3.crt" "http://www.cacert.org/certs/class3.crt"
    echo > .password
    mkdir -p .pki/nssdb
    CERT_DIR=sql:$HOME/.pki/nssdb
    certutil -N -d .pki/nssdb -f .password
    certutil -d ${CERT_DIR}  -A -t TC \
      -n "CAcert.org" -i cacert-root.crt
    certutil -d ${CERT_DIR} -A -t TC \
      -n "CAcert.org Class 3" -i cacert-class3.crt
    certutil -d sql:$HOME/.pki/nssdb -A \
      -n puffing-billy -t "CT,C,C" -i #{Billy.certificate_authority.cert_file}
  SCRIPT
end

# Setup the macOS certificate store
if OS.mac?
  prompt = 'Add Puffing Billy root certificate authority ' \
           'to system certificate store'
  system <<~SCRIPT
    sudo -p "# #{prompt}`echo $'\nPassword: '`" \
      security find-certificate -a -Z -c 'Puffing Billy' \
      | grep 'SHA-1 hash' | cut -d ':' -f2 | xargs -n1 \
      sudo security delete-certificate -Z >/dev/null 2>&1 || true
    sudo security add-trusted-cert -d -r trustRoot \
      -k /Library/Keychains/System.keychain \
      #{Billy.certificate_authority.cert_file}
  SCRIPT
end
```

Mind the reset of the `HOME` environment variable. Fortunately Chrome takes
care of the users home, so we can setup a new temporary directory for the test
run, without messing with potential user configurations.

The macOS support requires the input of your password to manipulate the system
certificate store. If you are lazy you can turn off sudo password prompt for
the security command, but it's strongly advised against. (You know passwordless
security, is no security in this case) Further, the macOS handling here cleans
up old Puffing Billy root certificate authorities and put the current one into
the system store. So after a run of your the suite only one certificate will be
left over. If this is not enough you can handling the cleanup again with a
custom on-after hook.

## Resources

* [Bring Ruby VCR to Javascript testing with Capybara and puffing-billy](http://architects.dzone.com/articles/bring-ruby-vcr-javascript)
* [Integration Testing Stripe.js With Mocked Network Requests](http://dev.contractual.ly/testing-stripe-js-with-mocked-network/)
* [Clean-up unused cache files periodically with this config](https://github.com/oesmith/puffing-billy/pull/26#issuecomment-29905030)

## FAQ

1. Why name it after a train?

   Trains are *cool*.

## Contributing

1. Fork it
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Commit your changes (`git commit -am 'Added some feature'`)
4. Push to the branch (`git push origin my-new-feature`)
5. Create new Pull Request

## TODO

1. Integration for test frameworks other than rspec.
2. Show errors from the EventMachine reactor loop in the test output.