Testing REST APIs with Cucumber and Rack::Test

# First attempting to use Capybara directly, you will ran into issues when trying to set HTTP header.
# Using Basic HTTP Authentication requires that we needed to set the header.
# Also we need to set the Content-Type and Accept headers to ensure that Rails handles the input and output correctly.
# When using Rack, Capybara delegates request and response handling down to Rack::Test. 
# So I used Rack::Test directly in my step definitions, and it works.
# Rack::Test has a module called Rack::Test::Methods that can be mixed into a class to provide it
# with methods for get, post, put, delete as well as last_request, last_response, header and more. 
# I mixed Rack::Test::Methods into the Cucumber world at the top of our API steps file like so:

##############################
#features/list_domiain.feature

@api
Feature: List domains
  As an API client
  In order to do things with domains
  I want to retrieve a list of domains

  Scenario: retreive all domains as XML
    Given I am a valid API user
    And I send and accept XML
    And I have 1 domain with 5 "A" records
    When I send a GET request for "/domains"
    Then the response should be "200"
    And the XML response should be a "domains" array with 1 "domain" elements

  Scenario: retreive all domains as JSON
    Given I am a valid API user
    And I send and accept JSON
    And I have 1 domain with 5 "A" records
    When I send a GET request for "/domains"
    Then the response should be "200"
    And the JSON response should be an array with 1 "domain" elements

##############################################
#features/step_definitions/list_domain_steps.rb

World(Rack::Test::Methods)

Given /^I am a valid API user$/ do
  @user = Factory(:user)
  authorize(@user.email, @user.password)
end

Given /^I send and accept XML$/ do
  header 'Accept', 'text/xml'
  header 'Content-Type', 'text/xml'
end

Given /^I send and accept JSON$/ do
  header 'Accept', 'application/json'
  header 'Content-Type', 'application/json'
end

When /^I send a GET request for "([^\"]*)"$/ do |path|
  get path
end

When /^I send a POST request to "([^\"]*)" with the following:$/ do |path, body|
  post path, body
end

When /^I send a PUT request to "([^\"]*)" with the following:$/ do |path, body|
  put path, body
end

When /^I send a DELETE request to "([^\"]*)"$/ do |path|
  delete path
end

Then /^the response should be "([^\"]*)"$/ do |status|
  last_response.status.should == status.to_i
end

Then /^the XML response should be a "([^\"]*)" array with (\d+) "([^\"]*)" elements$/ do |tag, number_of_children, child_tag|
  page = Nokogiri::XML(last_response.body)
  page.xpath("//#{tag}/#{child_tag}").length.should == number_of_children.to_i
end

Then /^the JSON response should be an array with (\d+) "([^\"]*)" elements$/ do |number_of_children, name|
  page = JSON.parse(last_response.body)
  page.map { |d| d[name] }.length.should == number_of_children.to_i
end