Tealeaf Academy course three/week seven - payments with Stripe part 3 - testing

In my previous post I went over some of the changes I made to receive Stripe payments in my application and today I'm going to go over ways to test this. I had previously used the stripe-ruby-mock gem which saves a lot of time and effort but I also want to learn the skills of how to write tests myself that can be used to test a 3rd party service.

(Click on the link to read my last post on the Payments With Stripe Part 2).

Payment Tests

The first thing I want to test is the ExternalPaymentProcessor class which looks as follows:

class ExternalPaymentProcessor
  require "#{Rails.root}/lib/stripe_payment_processor.rb"

  attr_accessor :processed, :error

  def self.create_payment_process(options={})
    response = payment_processor.new(options).process_card
    response == true ? new(processed: response) : new(error: response)


  def initialize(options={})
    @processed = options[:processed]
    @error = options[:error]

  def self.payment_processor


I wanted to test this to check that payments work with valid card details and also that there is an error message and no charge if there are invalid card details. I won't go into too much detail of the actual test for this rather explain a gem I used called vcr. The first time I run the tests, the payment providers servers will be hit but vcr will record this first test. Any future tests will then just re-run this recording and not actually hit the servers of the payment provider. Therefore the tests will run a lot faster.

In order to use vcr I need to configure it in my spec_helper file:

VCR.configure do |c|
  c.allow_http_connections_when_no_cassette = true
  c.cassette_library_dir = 'spec/cassettes'
  c.hook_into :webmock
  c.ignore_localhost = true

and also add the following:

RSpec.configure do |config|
  config.treat_symbols_as_metadata_keys_with_true_values = true

I will explain the configuration options I have used. Setting allow_http_connections_when_no_cassette means I can dictate whether I want to allow HTTP requests. Usually, HTTP requests made when no cassette is inserted will result in an error. cassette_library_dir is where the recording will be stored. hook_into determines how vcr hooks into the HTTP requests to record and replay them. For vcr to work I'm using the webmock gem which ties in at the HTTP request level, letting me define mock responses. For the first request, vcr will allow a real HTTP request but will record the response. Webmock will then prevent all subsequent HTTP requests and pass back the recorded response that is stored in 'spec/cassettes'. configure_rspec_metadata! helps vcr to integrate with RSpec using metadata. By passing :vcr as an additional argument after the description string it will use set the cassette name based on the example's full description. For example take the follow section of a test:

describe ExternalPaymentProcessor do

  describe :charge do

    context "with valid card details" do
      it "makes a successful charge", :vcr do

By passing :vcr the cassette will be stored at

spec/cassettes/ExternalPaymentProcessor/charge/with valid card details/makes a successful charge.yml

Setting treat_symbols_as_metadata_keys_with_true_values = true means that you can pass in :vcr rather than vcr: true.

The ignore_localhost configuration option can be used to prevent VCR from having any affect on localhost requests. If set to true, it will never record them and always allow them.

Controller Tests

The important part of my last post for testing was my create action for UsersController:

def create
  @user = User.new(user_params)
  if @user.valid?
    attempt_card_payment = registration_payment_processor
    if attempt_card_payment.processed
      flash[:success] = "Thank you for registering, please sign in."
      redirect_to sign_in_path
    handle_create_error("Please fix the errors in this form.")


def registration_payment_processor
    amount: 999,
    email: @user.email_address,
    token: params[:stripeToken]

def handle_create_error(error)
  flash[:danger] = error
  render :new

You can see in my code that attempt_card_payment is equal to registration_payment_processor which instantiates the ExternalPaymentProcessor class. I won't go into the details of that here although you can read the last post for more info on it. All you need to know is that this will hit the external servers of my payment provider (Stripe in this case). I want to be able to run my tests for the UsersController without actually hitting the servers. I can test the interaction with the payment provider in the ExternalPaymentProcessor tests but that's not what I need to test here. In this case I'm just interested in verifying that the flow of the create method works as expected.

In order to stop ExternalPaymentProcessor hitting the external servers I will use what are known as doubles and stubs in RSpec.

A test double is a simplified object which takes the place of another object in a test. In this case I want a double to take the place of attempt_card_payment. As an example, take this snippet of my code:

describe "POST create" do
  context "valid personal details" do

    context "valid card details" do

      let(:attempt_card_payment) { double(:attempt_card_payment) }
      before do
        expect(attempt_card_payment).to receive(:processed).and_return(true)
        allow(ExternalPaymentProcessor).to receive(:create_payment_process).and_return(attempt_card_payment) 

As you can see, I have defined the double :attempt_card_payment and also asserted that I want :processed to return true for this test because I am testing valid card details. Lastly I also want to stub the create_payment_process on ExternalPaymentProcessor to let it return whatever I like without ever hitting the external payment provider servers. Stubbing is also really useful for TDD because it lets me specify the code I want to have without relying on code that’s already there.

Feature Tests

Lastly I want to talk through my feature test for when a user registers on my site. I have been using Capybara for my feature tests which works well but this particular page I am testing includes javascript for the payment process. I will show a snippet of my code below and explain how to make it all work:

require 'spec_helper'

feature "User registers", js: true, vcr: true do
  background do 
    visit register_path 

  context "with valid personal info" do
    scenario "with valid card info" do

      expect(page).to have_content("Thank you for registering, please sign in.")

I have already talked about vcr but also note that I have set js: true which switches to the Capybara.javascript_driver which is :selenium by default. You can read more about the drivers available here. I used both selenium and poltergeist for my feature tests. Selenium is really handy when you need to debug because it opens the browser when it's running the tests and you can visually see what is happening. However it is also very slow so when I'm done debugging I switch over to poltergeist. I initially used capybara-webkit but found it to not be as reliable so I switched to poltergeist. For this to work I need to install both the selenium and poltergeist gems: gem 'selenium-webdriver' and gem 'poltergeist' and then in my spec_helper file I added in Capybara.javascript_driver = :poltergeist to make poltergeist my default choice. However, if I wanted to run selenium on an individual test then I could just add it into that test like so:

feature "User registers", js: true, vcr: true, driver: :selenium do

There are a couple of additions I need to make for selenium. Selenium will run on a port other than 3000 so in spec_helper also add:

Capybara.server_port = 52662

Additionally, in config/environments/test.rb you need to change config.action_mailer.default_url_options = { host: 'localhost:3000' } to config.action_mailer.default_url_options = { host: 'localhost:52662' }.

I also alter the default Capybara wait time for my tests because they sometimes wouldn't complete in the default 2 seconds so for that simply add to spec_helper:

Capybara.default_wait_time = 5

Lastly, if you use selenium you will also need to install gem 'database_cleaner' in order to clean the database. You can read more about this here but I'll show the settings in spec_helper to make it work:

RSpec.configure do |config|

  config.treat_symbols_as_metadata_keys_with_true_values = true

  config.before(:suite) do

  config.before(:each) do
    DatabaseCleaner.strategy = :transaction

  config.before(:each, :js => true) do
    DatabaseCleaner.strategy = :truncation

  config.before(:each) do

  config.after(:each) do

  config.use_transactional_fixtures = false

This is explained much better than I ever could in the last article I linked to so make sure to check it out!

That's it for this post but hopefully this will save you time with setting up your tests because there was quite a few steps to work through for this especially when javascript is involved.