Cucumber capybara stubbing

Question

I have an index action in a rails controller called images_controller.rb that fetches images from an external service. I am trying to write cucumber scenarios and am struggling with how to write/stub out my visit index page step. How could I stub out the images it fetches without it making the request?

Feature:

Scenario: Image Index
  Given an image exists on the image server
  When I am on the images page
  Then I should see images

Steps so far:

Given(/^an image exists on the image server$/) do
  image_server_url = IMAGE_SERVER['base_url'] + "/all_images"
  image = "image.png"
  image_path = "development_can/image.png"
  response = [{image_path => [image]}].to_json
  stub_request(:get, image_server_url).to_return(JSON.parse(response))
end

When(/^I am on the images page$/) do
  body = "[{\"image/development_app\":[\"the_pistol.jpeg\"]},{\"image/development_can\":[\"kaepernick.jpg\"]}]"
  @images = JSON.parse(body)
end

Then(/^I should see images$/) do

end

controller:

class ImagesController < ApplicationController
  def index
    response = image_server_connection.get(IMAGE_SERVER['base_url'] + "/all_images")
    @images = JSON.parse(response.body)
  end
end

Answer 1

Generally speaking, Cucumber specs are "full-stack integration tests", meaning you really don't want to stub anything out unless absolutely necessary. If you do stub those calls out, how would you know if all of a sudden the external service stopped behaving the way you expect it to?

That said, in order to stub it, you'd want to stub the method get on the object returned by the controller method image_server_connection.