[Serverspec] running tests inside a Docker container

docker_in_serverspec.rb

require 'spec_helper'

# the root folder should contain Dockerfile so build_from_dir can work

describe "mycontainer" do
  before(:all) do
    image = Docker::Image.build_from_dir('.')
    @container = image.run()
    set :os, family: :debian
    set :backend, :docker
    set :docker_container, @container.id
  end

  describe command('sleep 1') do
    its(:exit_status) { should eq 0 }
  end

  after(:all) do
     @container.kill
     @container.delete(:force => true)
  end
end

Gemfile for this:

source "https://rubygems.org"

gem 'docker-api'
gem 'serverspec'