test(subscription): add user subscription flow

When there's no user logged in.

spec/features/subscriptions_spec.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe 'Subscriptions', type: :feature do
+  context 'without a user account' do
+    let!(:plan) { FactoryBot.create(:plan) }
+    let(:new_user) { FactoryBot.attributes_for(:user) }
+
+    it 'allows going through the flow and prompts for a user account creation' do
+      visit '/'
+      expect(page).to have_content('Welcome to app!')
+      expect(page).to have_content(plan.name)
+
+      within "#subscription-#{plan.name.parameterize.underscore}" do
+        click_link 'Subscribe'
+      end
+
+      expect(page).to have_content(plan.name)
+
+      click_button 'Start Donating'
+
+      expect(page).to have_content('Please create an account')
+
+      # create account
+      fill_in 'First name', with: new_user[:first_name]
+      fill_in 'Last name', with: new_user[:last_name]
+      fill_in 'Email', with: new_user[:email]
+
+      click_button 'Continue'
+
+      # payment details
+      expect(page).to have_content('Payment')
+
+      # TODO: Add Stripe elements
+
+      click_link 'Finish'
+
+      expect(page).to have_content('Subscription was successfully added.')
+    end
+  end
+end