Refactor segment constant into a class method

We're going to make it dynamic using the geozones. Besides, class
methods can be overwritten using custom models, while constants can't be
overwritten without getting a warning [1].

Makes the definition of segments with geozones a little cleaner. I
think it’s worth it, compared to the slight memory gain of using a
constant [2].

[1] warning: already initialized constant UserSegments::SEGMENTS

[2] https://stackoverflow.com/questions/15903835/class-method-vs-constant-in-ruby-rails#answer-15903970

app/helpers/user_segments_helper.rb

@@ -1,6 +1,6 @@
 module UserSegmentsHelper
   def user_segments_options
-    UserSegments::SEGMENTS.map do |user_segment_name|
+    UserSegments.segments.map do |user_segment_name|
       [t("admin.segment_recipient.#{user_segment_name}"), user_segment_name]
     end
   end

db/dev_seeds/newsletters.rb

@@ -14,7 +14,7 @@ section "Creating Newsletters" do
   5.times do |n|
     Newsletter.create!(
       subject: "Newsletter subject #{n}",
-      segment_recipient: UserSegments::SEGMENTS.sample,
+      segment_recipient: UserSegments.segments.sample,
       from: "no-reply@consul.dev",
       body: newsletter_body.sample,
       sent_at: [Time.current, nil].sample

lib/user_segments.rb

@@ -1,5 +1,6 @@
 class UserSegments
-  SEGMENTS = %w[all_users
+  def self.segments
+    %w[all_users
        administrators
        all_proposal_authors
        proposal_authors
@@ -8,6 +9,7 @@ class UserSegments
        selected_investment_authors
        winner_investment_authors
        not_supported_on_current_budget].freeze
+  end
 
   def self.all_users
     User.active.where.not(confirmed_at: nil)

spec/factories/emails.rb

@@ -1,7 +1,7 @@
 FactoryBot.define do
   factory :newsletter do
     sequence(:subject) { |n| "Subject #{n}" }
-    segment_recipient  { UserSegments::SEGMENTS.sample }
+    segment_recipient  { UserSegments.segments.sample }
     sequence(:from)    { |n| "noreply#{n}@consul.dev" }
     sequence(:body)    { |n| "Body #{n}" }
   end

spec/factories/notifications.rb

@@ -24,7 +24,7 @@ FactoryBot.define do
     sequence(:title)  { |n| "Admin Notification title #{n}" }
     sequence(:body)   { |n| "Admin Notification body #{n}" }
     link              { nil }
-    segment_recipient { UserSegments::SEGMENTS.sample }
+    segment_recipient { UserSegments.segments.sample }
     recipients_count  { nil }
     sent_at           { nil }
 

spec/system/admin/admin_notifications_spec.rb

@@ -215,7 +215,7 @@ describe "Admin Notifications", :admin do
   end
 
   scenario "Select list of users to send notification" do
-    UserSegments::SEGMENTS.each do |user_segment|
+    UserSegments.segments.each do |user_segment|
       segment_recipient = I18n.t("admin.segment_recipient.#{user_segment}")
 
       visit new_admin_admin_notification_path

spec/system/admin/emails/newsletters_spec.rb

@@ -162,7 +162,7 @@ describe "Admin newsletter emails", :admin do
   end
 
   scenario "Select list of users to send newsletter" do
-    UserSegments::SEGMENTS.each do |user_segment|
+    UserSegments.segments.each do |user_segment|
       visit new_admin_newsletter_path
 
       fill_in_newsletter_form(segment_recipient: I18n.t("admin.segment_recipient.#{user_segment}"))