FEATURE: Implement max_tags_per_email_subject (#22050)

* FEATURE: Implement max_tags_per_email_subject

* made it so only max_tags_per_email_subject is responsible for tags in emails when the feature is enabled

* added locales for implemented siteSettings

* reworded locale for enable_max_tags_per_email_subject

* added min value for max_tags_per_email_subject

* Implemented suggested changes to spec description

app/mailers/user_notifications.rb

@@ -601,12 +601,19 @@ class UserNotifications < ActionMailer::Base
 
     # tag names
     if opts[:show_tags_in_subject] && post.topic_id
+      max_tags =
+        if SiteSetting.enable_max_tags_per_email_subject
+          SiteSetting.max_tags_per_email_subject
+        else
+          SiteSetting.max_tags_per_topic
+        end
+
       tags =
         DiscourseTagging
           .visible_tags(Guardian.new(user))
           .joins(:topic_tags)
           .where("topic_tags.topic_id = ?", post.topic_id)
-          .limit(SiteSetting.max_tags_per_topic)
+          .limit(max_tags)
           .pluck(:name)
 
       show_tags_in_subject = tags.any? ? tags.join(" ") : nil

config/locales/server.en.yml

@@ -2366,6 +2366,8 @@ en:
     tagging_enabled: "Enable tags on topics?"
     min_trust_to_create_tag: "The minimum trust level required to create a tag."
     max_tags_per_topic: "The maximum tags that can be applied to a topic."
+    enable_max_tags_per_email_subject: "Use max_tags_per_email_subject when generating the subject of an email"
+    max_tags_per_email_subject: "The maximum tags that can be in the subject of an email"
     max_tag_length: "The maximum amount of characters that can be used in a tag."
     max_tag_search_results: "When searching for tags, the maximum number of results to show."
     max_tags_in_filter_list: "Maximum number of tags to show in the filter dropdown. The most used tags will be shown."

config/site_settings.yml

@@ -2776,6 +2776,13 @@ tags:
   max_tags_per_topic:
     default: 5
     client: true
+  enable_max_tags_per_email_subject:
+    default: false
+    client: true
+  max_tags_per_email_subject:
+    default: 5
+    client: true
+    min: 0
   max_tag_length:
     default: 20
     client: true

spec/mailers/user_notifications_spec.rb

@@ -445,6 +445,7 @@ RSpec.describe UserNotifications do
     let(:category) { Fabricate(:category, name: "India") }
     let(:tag1) { Fabricate(:tag, name: "Taggo") }
     let(:tag2) { Fabricate(:tag, name: "Taggie") }
+    let(:tag3) { Fabricate(:tag, name: "Teggo") }
 
     let(:hidden_tag) { Fabricate(:tag, name: "hidden") }
     let!(:hidden_tag_group) do
@@ -455,7 +456,7 @@ RSpec.describe UserNotifications do
       Fabricate(
         :topic,
         category: category,
-        tags: [tag1, tag2, hidden_tag],
+        tags: [tag1, tag2, tag3, hidden_tag],
         title: "Super cool topic",
       )
     end
@@ -558,19 +559,49 @@ RSpec.describe UserNotifications do
       expect(mail_html.scan(/>bobmarley/).count).to eq(1)
     end
 
-    it "the number of tags shown in subject should match max_tags_per_topic" do
-      SiteSetting.email_subject =
-        "[%{site_name}] %{optional_pm}%{optional_cat}%{optional_tags}%{topic_title}"
-      SiteSetting.max_tags_per_topic = 1
-      mail =
-        UserNotifications.user_replied(
-          user,
-          post: response,
-          notification_type: notification.notification_type,
-          notification_data_hash: notification.data_hash,
-        )
-      expect(mail.subject).to match(/Taggo/)
-      expect(mail.subject).not_to match(/Taggie/)
+    describe "number of tags shown in subject line" do
+      describe "max_tags_per_email_subject siteSetting enabled" do
+        before { SiteSetting.enable_max_tags_per_email_subject = true }
+
+        it "should match max_tags_per_email_subject" do
+          SiteSetting.email_subject =
+            "[%{site_name}] %{optional_pm}%{optional_cat}%{optional_tags}%{topic_title}"
+          SiteSetting.max_tags_per_topic = 1
+          SiteSetting.max_tags_per_email_subject = 2
+          mail =
+            UserNotifications.user_replied(
+              user,
+              post: response,
+              notification_type: notification.notification_type,
+              notification_data_hash: notification.data_hash,
+            )
+          expect(mail.subject).to match(/Taggo/)
+          expect(mail.subject).to match(/Taggie/)
+          expect(mail.subject).not_to match(/Teggo/)
+        end
+      end
+
+      describe "max_tags_per_email_subject siteSetting disabled" do
+        before { SiteSetting.enable_max_tags_per_email_subject = false }
+
+        it "should match max_tags_per_topic" do
+          SiteSetting.email_subject =
+            "[%{site_name}] %{optional_pm}%{optional_cat}%{optional_tags}%{topic_title}"
+          SiteSetting.max_tags_per_topic = 2
+          SiteSetting.max_tags_per_email_subject = 1
+
+          mail =
+            UserNotifications.user_replied(
+              user,
+              post: response,
+              notification_type: notification.notification_type,
+              notification_data_hash: notification.data_hash,
+            )
+          expect(mail.subject).to match(/Taggo/)
+          expect(mail.subject).to match(/Taggie/)
+          expect(mail.subject).not_to match(/Teggo/)
+        end
+      end
     end
 
     it "doesn't include details when private_email is enabled" do