Example of using pact with webmock, i.e. to proxy connection via Rack application to mock service without changing base_url in client library

animal_service_client_spec.rb

require 'httparty'
require_relative 'pact_helper'
require 'webmock/rspec'
require 'byebug'
require 'rack/proxy'

WebMock.disable_net_connect!(allow_localhost: true)

class Alligator
  attr_reader :name

  def initialize name
    @name = name
  end

  def == other
    other.is_a?(Alligator) && other.name == name
  end
end

class AnimalServiceClient
  include HTTParty
  base_uri 'http://animal-service.com'

  def get_alligator
    name = JSON.parse(self.class.get("/alligator").body)['name']
    Alligator.new(name)
  end
end

class AnimalServiceRackApp < Rack::Proxy
  def rewrite_env(env)
    env['HTTP_HOST'] = 'localhost'
    env['SERVER_PORT'] = 1234
    env
  end
end

describe AnimalServiceClient, :pact => true do

  before do
    # Configure your client to point to the stub service on localhost using the port you have specified
    # AnimalServiceClient.base_uri 'localhost:1234'
    stub_request(:any, /animal-service.com/).to_rack(AnimalServiceRackApp.new(nil, streaming: false))
  end

  subject { AnimalServiceClient.new }

  describe "get_alligator" do
    before do
      animal_service.given("an alligator exists").
        upon_receiving("a request for an alligator").
        with(method: :get, path: '/alligator', query: '').
        will_respond_with(
          status: 200,
          headers: {'Content-Type' => 'application/json'},
          body: {name: 'Betty'} )
    end

    it "returns a alligator" do
      expect(subject.get_alligator).to eq(Alligator.new('Betty'))
    end
  end
end