agents_spec.rb

describe "GET /agents.json" do
  it_behaves_like "API controller", :params => { ... }, :environment => { ... }
end

api_context.rb

shared_context "API Controller", :as => :api do |params, environment|
  before do
    regexp = Regexp.new("(GET|PUT|POST|DELETE|HEAD) ([^ ]+)")
    if match = regexp.match(example.full_description)
      http_method  = match[1].downcase
      request_path = match[2]
      send(http_method, request_path, params, environment)
    else
      raise "#{example.full_description.inspect} doesn't match #{regexp.inspect}"
    end
  end

  subject {response}
end