sample.rb

require 'rubygems'
require 'sinatra'

before do
  
  @username = session[:username]
    p session
end

get '/' do
  "Hello" + @username.to_s
end

spec_sample.rb

require 'sample'  # <-- your sinatra app
require 'spec'
require 'rack/test'

set :environment, :test
set :sessions, true

describe 'The HelloWorld App' do
  include Rack::Test::Methods

  def app
    Sinatra::Application
  end

  it "should say hello using sessions attempt one" do
    get '/', {}, :sessions => {:username => "garren"}
    last_response.should be_ok
    last_response.body.should == 'Hello garren'
  end
  
  it "should say hello using sessions attempt one" do
     get '/', {}, { "rack.session" =>  { :username => 'garren'}}
     last_response.should be_ok
     last_response.body.should == 'Hello garren'
   end
end