Sinatra based domain redirect app

redirect_to_matcher.rb

class RedirectTo
  def initialize(expected, session)
    @expected = expected
    @session  = session
  end

  def matches?(visit_proc)
    instance_eval(&visit_proc)

    @status = @session.status_code
    @actual = @session.response_headers['Location']

    @status == 302 && @actual == @expected
  end

  def visiting(url)
    @session.driver.get(url)
  end

  def failure_message_for_should
    if @status != 302
      "Expected a 302 response but got a #{@status}"
    else
      "Expected a redirect to '#{@expected}' but got '#{@actual}'"
    end
  end

  def failure_message_for_should_not
    "Expected to not redirect to '#{@expected}' but did"
  end
end

def redirect_to(url)
  RedirectTo.new(url, page)
end

redirector.rb

# Required gems:
#
# * sinatra

require 'sinatra/base'

class Redirector < Sinatra::Base
  def self.domain(domain, &block)
    @domain = domain
    instance_eval(&block)
  end

  def self.redirect(source, location)
    get source, :host_name => @domain do
      redirect to(location)
    end
  end

  domain 'domain-1.example.com' do
    redirect '/path', 'http://example.com/path-for-domain-1'
  end

  domain 'domain-2.example.com' do
    redirect '/path', 'http://example.com/path-for-domain-2'
  end
end

redirector_spec.rb

# Required gems:
#
# * rspec
# * capybara

require 'redirector'

require 'capybara/rspec'
Capybara.app = Redirector

require 'redirect_to_matcher'

describe Redirector, :type => :request do
  specify do
    expect { visiting 'http://domain-1.example.com/path' }.to \
      redirect_to('http://example.com/path-for-domain-1')
  end

  specify do
    expect { visiting 'http://domain-2.example.com/path' }.to \
      redirect_to('http://example.com/path-for-domain-2')
  end
end