FEATURE: More granular mailing list mode (#4068)

* Rearrange frontend to account for mailing list mode

* Allow update of user preference for mailing list frequency

* Add mailing list frequency estimate

* Simplify frequency estimate; disable activity summary for mailing list mode

* Remove combined updates

* Add specs for enqueue mailing list mode job

* Write mailing list method for mailer

* Fix linting error

* Account for stale topics

* Add translations for default mailing list setting

* One query for mailing list topics

* Fix failing spec

* WIP

* Flesh out html template

* First pass at text-based mailing list summary

* Add user avatar

* Properly format posts for mailing list

* Move make_all_links_absolute into Email::Styles

* Apply first_seen_at to user

* Send mailing list email summary hourly based on first_seen_at

* Branch and test cleanup

* Use existing mailing list mode estimate

* Fix failing specs

spec/models/mailing_list_mode_site_setting_spec.rb

@@ -0,0 +1,17 @@
+require 'rails_helper'
+
+describe MailingListModeSiteSetting do
+  describe 'valid_value?' do
+    it 'returns true for a valid value as an int' do
+      expect(DigestEmailSiteSetting.valid_value?(0)).to eq true
+    end
+
+    it 'returns false for a valid value as a string' do
+      expect(DigestEmailSiteSetting.valid_value?('0')).to eq true
+    end
+
+    it 'returns false for an out of range value' do
+      expect(DigestEmailSiteSetting.valid_value?(3)).to eq false
+    end
+  end
+end

spec/models/user_spec.rb

@@ -596,6 +596,29 @@ describe User do
 
   end
 
+  describe "update_last_seen!" do
+    let (:user) { Fabricate(:user) }
+    let!(:first_visit_date) { Time.zone.now }
+    let!(:second_visit_date) { 2.hours.from_now }
+
+    it "should update the last seen value" do
+      expect(user.last_seen_at).to eq nil
+      user.update_last_seen!(first_visit_date)
+      expect(user.reload.last_seen_at).to be_within_one_second_of(first_visit_date)
+    end
+
+    it "should update the first seen value if it doesn't exist" do
+      user.update_last_seen!(first_visit_date)
+      expect(user.reload.first_seen_at).to be_within_one_second_of(first_visit_date)
+    end
+
+    it "should not update the first seen value if it doesn't exist" do
+      user.update_last_seen!(first_visit_date)
+      user.update_last_seen!(second_visit_date)
+      expect(user.reload.first_seen_at).to be_within_one_second_of(first_visit_date)
+    end
+  end
+
   describe "last_seen_at" do
     let(:user) { Fabricate(:user) }