Save opted_in_to_emails checkbox on sign up

app/controllers/registrations_controller.rb

 class RegistrationsController < Devise::RegistrationsController
   include Recaptcha::Verify
+  prepend EE::RegistrationsController
 
   def new
     redirect_to(new_user_session_path)

app/services/users/build_service.rb

 module Users
   class BuildService < BaseService
+    prepend ::EE::Users::BuildService
+
     def initialize(current_user, params = {})
       @current_user = current_user
       @params = params.dup

app/views/devise/shared/_signup_box.html.haml

@@ -22,6 +22,7 @@
         = f.label :password
         = f.password_field :password, class: "form-control bottom", required: true, pattern: ".{#{@minimum_password_length},}", title: "Minimum length is #{@minimum_password_length} characters."
         %p.gl-field-hint Minimum length is #{@minimum_password_length} characters
+      = render 'devise/shared/ee/email_opted_in', f: f
       %div
       - if Gitlab::Recaptcha.enabled?
         = recaptcha_tags

ee/app/controllers/ee/registrations_controller.rb

+module EE
+  module RegistrationsController
+    extend ActiveSupport::Concern
+    
+    private
+
+    def sign_up_params
+      params.require(:user).permit(:username, :email, :email_confirmation, :name, :password, :email_opted_in)
+    end
+  end
+end

ee/app/services/ee/users/build_service.rb

+module EE
+  module Users
+    module BuildService
+
+      private
+      
+      def signup_params
+        [
+          :email,
+          :email_confirmation,
+          :password_automatically_set,
+          :name,
+          :password,
+          :username,
+          :email_opted_in
+        ]
+      end
+    end
+  end
+end

ee/app/views/devise/shared/ee/_email_opted_in.html.haml

+- if Gitlab.com?
+  .form-group
+    = f.check_box :email_opted_in
+    = f.label :email_opted_in, "I'd like to receive updates via email about GitLab."

spec/ee/spec/features/signup_spec.rb

+require 'spec_helper'
+
+feature 'Signup on EE' do
+  context 'for Gitlab.com' do
+    before do
+      expect(Gitlab).to receive(:com?).and_return(true).at_least(:once)
+    end
+
+    context 'when the user checks the opt-in to email updates box' do
+      it 'creates the user and sets the email_opted_in field truthy' do
+        user = build(:user)
+
+        visit root_path
+
+        fill_in 'new_user_name',                with: user.name
+        fill_in 'new_user_username',            with: user.username
+        fill_in 'new_user_email',               with: user.email
+        fill_in 'new_user_email_confirmation',  with: user.email
+        fill_in 'new_user_password',            with: user.password
+        check   'new_user_email_opted_in'
+        click_button "Register"
+
+        user = User.find_by_username!(user.username)
+        expect(user.email_opted_in).to be_truthy
+      end
+    end
+
+    context 'when the user does not check the opt-in to email updates box' do
+      it 'creates the user and sets the email_opted_in field falsey' do
+        user = build(:user)
+
+        visit root_path
+
+        fill_in 'new_user_name',                with: user.name
+        fill_in 'new_user_username',            with: user.username
+        fill_in 'new_user_email',               with: user.email
+        fill_in 'new_user_email_confirmation',  with: user.email
+        fill_in 'new_user_password',            with: user.password
+        click_button "Register"
+
+        user = User.find_by_username!(user.username)
+        expect(user.email_opted_in).to be_falsey
+      end
+    end
+  end
+
+  context 'not for Gitlab.com' do
+    before do
+      expect(Gitlab).to receive(:com?).and_return(false).at_least(:once)
+    end
+
+    it 'does not have a opt-in checkbox, it creates the user and sets email_opted_in to falsey' do
+      user = build(:user)
+
+      visit root_path
+
+      expect(page).not_to have_selector("[name='new_user_email_opted_in']")
+
+      fill_in 'new_user_name',                with: user.name
+      fill_in 'new_user_username',            with: user.username
+      fill_in 'new_user_email',               with: user.email
+      fill_in 'new_user_email_confirmation',  with: user.email
+      fill_in 'new_user_password',            with: user.password
+      click_button "Register"
+
+      user = User.find_by_username!(user.username)
+      expect(user.email_opted_in).to be_falsey
+    end
+  end
+end