app.rb

require "rubygems"
gem     "sinatra", "=1.0"
require "sinatra/base"

class App < Sinatra::Base
  get "/direct" do
    params.inspect
  end
end

config.ru

require 'app'
run App

gistfile4.txt

Browsing to http://localhost:3333/direct?box[]=1&box[]=2
{"box"=>["1", "2"]}


> spec test.rb

1) 'requesting a url with [] params should include the contents of the params array' FAILED

expected "{\"box\"=>[\"1\", \"2\"]}"
     got "{\"box\"=>[nil, nil]}"

test.rb

require 'rubygems'
require 'rack/test'
require 'app'

Spec::Runner.configure do |config|
  config.include Rack::Test::Methods
end

def app
  @app ||= App
end

describe "requesting a url with [] params" do
  it "should include the contents of the params array" do
    get "/direct?box[]=1&box[]=2"
    last_response.body.should eql('{"box"=>["1", "2"]}')
  end
end