FEATURE: new site setting 'max_emojis_in_title'

app/models/topic.rb

@@ -84,6 +84,7 @@ class Topic < ActiveRecord::Base
                     topic_title_length: true,
                     censored_words: true,
                     quality_title: { unless: :private_message? },
+                    max_emojis: true,
                     unique_among: { unless: Proc.new { |t| (SiteSetting.allow_duplicate_topic_titles? || t.private_message?) },
                                     message: :has_already_been_used,
                                     allow_blank: true,

config/locales/server.en.yml

@@ -114,6 +114,7 @@ en:
       not_an_integer: must be an integer
       odd: must be odd
       record_invalid: ! 'Validation failed: %{errors}'
+      max_emojis: "can't have more than %{max_emojis_count} emoji"
       restrict_dependent_destroy:
         one: "Cannot delete record because a dependent %{record} exists"
         many: "Cannot delete record because dependent %{record} exist"
@@ -984,6 +985,7 @@ en:
     min_topic_title_length: "Minimum allowed topic title length in characters"
     max_topic_title_length: "Maximum allowed topic title length in characters"
     min_personal_message_title_length: "Minimum allowed title length for a message in characters"
+    max_emojis_in_title: "Maximum allowed emojis in topic title"
     min_search_term_length: "Minimum valid search term length in characters"
     search_tokenize_chinese_japanese_korean: "Force search to tokenize Chinese/Japanese/Korean even on non CJK sites"
     search_prefer_recent_posts: "If searching your large forum is slow, this option tries an index of more recent posts first"

config/site_settings.yml

@@ -502,6 +502,7 @@ posting:
     client: true
     default: 2
     min: 1
+  max_emojis_in_title: 1
   allow_uncategorized_topics:
     client: true
     default: true

lib/validators/max_emojis_validator.rb

@@ -0,0 +1,11 @@
+class MaxEmojisValidator < ActiveModel::EachValidator
+
+  def validate_each(record, attribute, value)
+    if Emoji.unicode_unescape(value).scan(/:([\w\-+]*(?::t\d)?):/).size > SiteSetting.max_emojis_in_title
+      record.errors.add(
+        attribute, :max_emojis,
+        max_emojis_count: SiteSetting.max_emojis_in_title
+      )
+    end
+  end
+end

spec/components/validators/max_emojis_validator_spec.rb

@@ -0,0 +1,50 @@
+# encoding: UTF-8
+
+require 'rails_helper'
+require 'validators/max_emojis_validator'
+
+describe MaxEmojisValidator do
+
+  # simulate Rails behavior (singleton)
+  def validate
+    @validator ||= MaxEmojisValidator.new(attributes: :title)
+    @validator.validate_each(record, :title, record.title)
+  end
+
+  shared_examples "validating any topic title" do
+    it 'adds an error when emoji count is greater than SiteSetting.max_emojis_in_title' do
+      SiteSetting.max_emojis_in_title = 3
+      record.title = '🧐 Lots of emojis here 🎃 :joy: :sunglasses:'
+      validate
+      expect(record.errors[:title]).to be_present
+    end
+  end
+
+  describe 'topic' do
+    let(:record) { Fabricate.build(:topic) }
+
+    it 'does not add an error when emoji count is good' do
+      SiteSetting.max_emojis_in_title = 2
+
+      record.title = 'To Infinity and beyond! 🚀 :woman:t5:'
+      validate
+      expect(record.errors[:title]).to_not be_present
+    end
+
+    include_examples "validating any topic title"
+  end
+
+  describe 'private message' do
+    let(:record) { Fabricate.build(:private_message_topic) }
+
+    it 'does not add an error when emoji count is good' do
+      SiteSetting.max_emojis_in_title = 1
+
+      record.title = 'To Infinity and beyond! 🚀'
+      validate
+      expect(record.errors[:title]).to_not be_present
+    end
+
+    include_examples "validating any topic title"
+  end
+end