Song Service Spec with Double

song_service_spec.rb

RSpec.describe SongService do
  require 'spec_helper'

  subject { SongService.new(gateway_service: gateway_service) }
  let(:song) { Song.new(name: 'Seek Up', artist: 'Dave Matthews Band', genre: 'Rock') }

  context 'using doubles' do
    let(:gateway_service) do
      stub = double("gateway_service")

      allow(stub).to receive(:create_song) do
        Song.new(name: song.name, artist: song.artist, genre: song.genre, id: 'abc').to_json
      end

      stub
    end

    it 'creates a valid song' do
      new_song = subject.create_song(song)
      expect(new_song.name).to eq song.name
      expect(new_song.artist).to eq song.artist
      expect(new_song.genre).to eq song.genre
      expect(new_song.id).to_not be_nil
      expect(new_song.id).to_not eq song.id
    end
  end
end