Testing a rack-mount router

router.rb

require 'rack/lobster'

module App
  class Router
    def initialize
      @app = Rack::Mount::RouteSet.new do |set|
        set.add_route ->(*args) { Rack::Lobster.new.call(*args) }, { :request_method => 'GET', :path_info => %r{^/lobster$} }, {}, :lobster
      end
    end

    def call(*args)
      @app.call(*args)
    end
  end
end

router_spec.rb

require 'spec_helper'

module App
  describe Router do
    let(:lobster) { mock(Rack::Lobster, call: [ 200, { }, [ ] ]) }

    subject { Router.new }

    let(:session) { Rack::Test::Session.new(subject) }

    before(:each) do
      Rack::Lobster.stub(new: lobster)
    end

    it "routes the lobster" do
      lobster.should_receive(:call)
      session.get("/lobster")
    end
  end
end