Subscription URL to point to staging for test and dev env

ee/lib/ee.rb

 # frozen_string_literal: true
 
 module EE
-  SUBSCRIPTIONS_URL = ENV.fetch('CUSTOMER_PORTAL_URL', 'https://customers.gitlab.com').freeze
+  def self.default_subscriptions_url
+    ::Gitlab.dev_or_test_env? ? 'https://customers.stg.gitlab.com' : 'https://customers.gitlab.com'
+  end
+
+  SUBSCRIPTIONS_URL = ENV.fetch('CUSTOMER_PORTAL_URL', default_subscriptions_url).freeze
   SUBSCRIPTIONS_COMPARISON_URL = "https://about.gitlab.com/pricing/gitlab-com/feature-comparison".freeze
   SUBSCRIPTIONS_MORE_MINUTES_URL = "#{SUBSCRIPTIONS_URL}/buy_pipeline_minutes".freeze
   SUBSCRIPTIONS_MORE_STORAGE_URL = "#{SUBSCRIPTIONS_URL}/buy_storage".freeze

ee/spec/lib/ee_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe EE do
+  describe '.default_subscriptions_url' do
+    subject { EE.default_subscriptions_url }
+
+    context 'on non test and non dev environments' do
+      before do
+        allow(Rails).to receive_message_chain(:env, :test?).and_return(false)
+        allow(Rails).to receive_message_chain(:env, :development?).and_return(false)
+      end
+
+      it 'returns production subscriptions app URL' do
+        is_expected.to eq('https://customers.gitlab.com')
+      end
+    end
+
+    context 'on dev environment' do
+      before do
+        allow(Rails).to receive_message_chain(:env, :test?).and_return(false)
+        allow(Rails).to receive_message_chain(:env, :development?).and_return(true)
+      end
+
+      it 'returns staging subscriptions app url' do
+        is_expected.to eq('https://customers.stg.gitlab.com')
+      end
+    end
+
+    context 'on test environment' do
+      before do
+        allow(Rails).to receive_message_chain(:env, :test?).and_return(true)
+        allow(Rails).to receive_message_chain(:env, :development?).and_return(false)
+      end
+
+      it 'returns staging subscriptions app url' do
+        is_expected.to eq('https://customers.stg.gitlab.com')
+      end
+    end
+  end
+end