Sinatra with RSpec config,

Gemfile

source 'https://rubygems.org'
ruby '2.0.0'

gem 'sinatra'
gem 'rspec'
gem 'rack-test'

myapp_spec.rb

require 'myapp'
require 'spec_helper'

set :environment, :test

describe 'The MyApp site' do

  it "returns somthing on the root url" do
    get '/'
    last_response.should be_ok
    expect(last_response.body).to include "html"
  end

end

spec_helper.rb

require './myapp'
require 'rspec'
require 'rack/test'

def app
  MyAppClassName
end

# This file was generated by the `rspec --init` command. Conventionally, all
# specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
# Require this file using `require "spec_helper"` to ensure that it is only
# loaded once.
#
# See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
RSpec.configure do |config|
  config.include Rack::Test::Methods
  config.treat_symbols_as_metadata_keys_with_true_values = true
  config.run_all_when_everything_filtered = true
  # config.filter_run :focus

  # Run specs in random order to surface order dependencies. If you find an
  # order dependency and want to debug it, you can fix the order by providing
  # the seed, which is printed after each run.
  #     --seed 1234
  config.order = 'random'
end

1. Generate spec folder and helpers from rspec --init
2. Add config.include Rack::Test::Methods, correct requires and def app; MyApp; end
3. Run with rspec