Testing REST APIs with Cucumber and Rack::Test

README.md

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:

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

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