API stubbing for frontend testing: proxy method

proxy.rb

require 'ap'
require 'json'
require 'webrick'
require 'webrick/httpproxy'

# API stubbing for frontend testing: proxy method
# Thorsten Bosbach 03/2018

if ARGV.count != 3
  ap "Usage: ruby proxy.rb port request-path file"
  # ruby proxy.rb 7070 /notification-center/api/nc profiles_vomp_mixed_aggregated.json
  return
end

puts "port: #{ARGV[0]}\n"
puts "path: #{ARGV[1]}\n"
puts "file: #{ARGV[2]}\n"

handler = proc do |req, res|
  # save original body response to file for edit
  if req.path != nil
    ap req.path
    path = req.path.gsub '/', '_'
    file = File.expand_path("../#{path}", __FILE__)
    open(file, 'w') { |f|
      f.puts res.body
    }
  end
  # act on defined path
  if req.path == "#{ARGV[1]}" then
    file = File.expand_path("../#{ARGV[2]}", __FILE__)
    http_body = File.read(file)
    JSON.parse(http_body) # 'validation'
    res.body = http_body

    res.content_type = 'application/json'
    res.status = '200'
    res.header.delete('content-encoding')
    res.header.delete('etag') # no caching in browser
  end
end

# https://stackoverflow.com/questions/4996170/handle-the-put-method-in-webrick
class CustomWEBrickProxyServer < WEBrick::HTTPProxyServer
  # prevent ERROR unsupported method `PUT'.
  def do_PUT(req, res)
    perform_proxy_request(req, res) do |http, path, header|
      http.put(path, req.body || "", header)
    end
  end
  # This method is not needed for PUT but I added for completeness
  def do_OPTIONS(req, res)
    res['allow'] = "GET,HEAD,POST,OPTIONS,CONNECT,PUT"
  end
end

proxy = CustomWEBrickProxyServer.new Port: ARGV[0], ProxyContentHandler: handler, AccessLog: [], Logger: WEBrick::Log.new(nil)

trap 'INT'  do proxy.shutdown end
trap 'TERM' do proxy.shutdown end
trap 'SIGINT' do proxy.shutdown end

proxy.start