OAuth2 refresh_token testing

Gemfile

group :test do
  ...
  gem 'timecop'
  ...
end

oauth_controller_spec.rb

describe "expires_at" do
  it "should allow access with valid token" do
    request.env['Authorization'] = "OAuth #{@user.authentication_token}"
    get :messages
    response.code.should eql 200
  end
  it "should not allow access with expired token" do
    Timecop.freeze(Time.at(Time.now + @user.expires_at.seconds)) do 
      request.env['Authorization'] = "OAuth #{@user.authentication_token}"
      get :messages
      response.code.should eql 401
    end
  end
end