Here's my implementation using a 'fake' to simulate a call to the Instagram API. It's very similar to the Hashtag app example, with the exception of the FakeInstagram class where I didn't create a '.[]=' method since I'm not really searching for different terms like you would using Twitter. The actual Instagram response uses Hashie::Mash which I…

fake_instagram.rb

class FakeInstagram

  def self.client(opts = {})
    instagram_response = Hashie::Mash.new
    instagram_response.images!.thumbnail!.url = "someawesomeimage.jpg"
    OpenStruct.new(user_recent_media: [instagram_response])
  end
end

fake_instagram_spec.rb

require 'spec_helper'

describe FakeInstagram, '.client' do
  it 'returns an object that responds to recent media query just like Instagram' do
    user = create(:user)
    fake = FakeInstagram.client(user.access_token)
    expect(fake.user_recent_media).to be_an Array
    expect(fake.user_recent_media.length).to eq 1
    expect(fake.user_recent_media.first).to be_a Hashie::Mash
  end
end

photo_searcher.rb

class PhotoSearcher
  class_attribute :photo_service
  self.photo_service = Instagram
  attr_accessor :media

  def initialize(user)
    @media = photo_service.client(access_token: user.access_token).user_recent_media
  end

  def thumbnail_urls
    @media.map do |photo|
      photo.images.thumbnail.url
    end
  end
end

photo_searcher_spec.rb

require 'spec_helper'

describe PhotoSearcher, '#media' do
  it 'returns latest photos from Instagram' do
    user = create(:user)
    photo_searcher = PhotoSearcher.new(user)
    photos = photo_searcher.thumbnail_urls

    expect(photos.length).to be 20
  end
end

describe PhotoSearcher, 'using a custom photo service' do
  it 'returns results from the photo service passed in when querying for recent media' do
    media_results = stub('user recent media', user_recent_media: [1,2,3])
    fake_photo_service = stub('fake photo service', client: media_results)
    PhotoSearcher.photo_service = fake_photo_service

    user = create(:user)
    photo_service = PhotoSearcher.new(user)
    expect(photo_service.media).to eq media_results.user_recent_media
  end
end

user_adds_a_product_spec.rb

require 'spec_helper'  

feature 'User adds a product' do

  # ...

  scenario 'with photos taken from Instagram' do
    user_signs_in_and_clicks_sell

    user_should_see_image('distilleryimage', 20)
  end


  scenario 'with photos from a custom photo service' do
    PhotoSearcher.photo_service = FakeInstagram

    user_signs_in_and_clicks_sell

    user_should_see_image('someawesomeimage.jpg', 1)
  end

  def user_signs_in_and_clicks_sell
    user = create(:user)
    sign_in_with_omniauth
    click_link 'Sell'
  end

  def user_should_see_image(url_text, count)
    expect(page).to have_css 'li.photo', count: count
    photo_url = find('input#photo_0').value
    expect(photo_url).to match /#{url_text}/
  end
end