Glint + WEBrick で一時的なWebサーバを立ててテストする ref: http://qiita.com/uchiko/items/5af8a8e643ba94a3dc8e

file0.txt

.
├── Gemfile
├── Rakefile
└── spec
    ├── lib
    │   └── foo_spec.rb
    ├── servers
    │   └── httpserver.rb
    └── spec_helper.rb

file6.txt

$ bundle install
$ bundle exec -- rake

foo_spec.rb

require 'spec_helper'

describe 'foo' do
    include_context 'httpserver'
    before { @res = client.get('/foo') }
    it { expect(@res.body).to be == 'foo' }
end

Gemfile

source 'https://rubygems.org'

gem 'glint'
gem 'rake'
gem 'rspec'

httpserver.rb

# Glintで一時的なWebサーバを生成
server = Glint::Server.new do |port|

  # WEBrickでWebサーバを生成
  require 'webrick'
  http = WEBrick::HTTPServer.new({
    :BindAddress => '127.0.0.1',
    :Port => port
  })
  http.mount_proc('/foo') do |req, res|
    body = 'foo'

    res.content_length = body.size
    res.content_type = 'text/plain'
    res.body = body
  end
  trap(:INT) { http.shutdown }
  trap(:TERM) { http.shutdown }
  http.start
end
server.start

# 立ち上げたサーバの Host と Port の情報を保存
Glint::Server.info[:httpserver] = {
  host: "127.0.0.1",
  port: server.port,
}

Rakefile

require 'rspec/core'
require 'rspec/core/rake_task'
RSpec::Core::RakeTask.new(:spec) do |spec|
  spec.pattern = FileList['spec/**/*_spec.rb']
  spec.ruby_opts = %w[-w]
end

task :default => :spec

spec_helper.rb

$LOAD_PATH.unshift '../../lib'

# サーバ起動のスクリプトを読み込む
require 'glint'
Dir[File.expand_path("../servers/*.rb", __FILE__)].each {|f| require f}

# テストで使うHTTPクライアントを生成する
require 'rspec'
shared_context 'httpserver' do
  require 'net/http'
  let(:client) {
    Net::HTTP.new(
      Glint::Server.info[:httpserver][:host],
      Glint::Server.info[:httpserver][:port]
    )
  }
end

RSpec.configure do |config|
end