FEATURE: topic title is validated for blocked words (#8127)

Currently, the topic is only validated for censored words and should be validated for blocked words as well.

Blocked word validation is now used by both Post and Topic. To avoid code duplication, I extracted blocked words validation code into separate Validator, and use it in both places.

The only downside is that even if the topic contains blocked words validation message is saying "Your post contains a word that's not allowed: tomato" but I think this is descriptive enough.

app/models/topic.rb

@@ -74,6 +74,7 @@ class Topic < ActiveRecord::Base
                     presence: true,
                     topic_title_length: true,
                     censored_words: true,
+                    watched_words: true,
                     quality_title: { unless: :private_message? },
                     max_emojis: true,
                     unique_among: { unless: Proc.new { |t| (SiteSetting.allow_duplicate_topic_titles? || t.private_message?) },

lib/validators/post_validator.rb

@@ -36,7 +36,7 @@ class Validators::PostValidator < ActiveModel::Validator
     return if options[:skip_post_body] || post.topic&.pm_with_non_human_user?
     stripped_length(post)
     raw_quality(post)
-    watched_words(post)
+    WatchedWordsValidator.new(attributes: [:raw]).validate(post) if !post.acting_user&.staged
   end
 
   def stripped_length(post)
@@ -59,19 +59,6 @@ class Validators::PostValidator < ActiveModel::Validator
     post.errors.add(:raw, I18n.t(:is_invalid)) unless sentinel.valid?
   end
 
-  def watched_words(post)
-    if !post.acting_user&.staged && matches = WordWatcher.new(post.raw).should_block?.presence
-      if matches.size == 1
-        key = 'contains_blocked_word'
-        translation_args = { word: matches[0] }
-      else
-        key = 'contains_blocked_words'
-        translation_args = { words: matches.join(', ') }
-      end
-      post.errors.add(:base, I18n.t(key, translation_args))
-    end
-  end
-
   # Ensure maximum amount of mentions in a post
   def max_mention_validator(post)
     return if post.acting_user.try(:staff?)

lib/validators/watched_words_validator.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class WatchedWordsValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    if matches = WordWatcher.new(value).should_block?.presence
+      if matches.size == 1
+        key = 'contains_blocked_word'
+        translation_args = { word: matches[0] }
+      else
+        key = 'contains_blocked_words'
+        translation_args = { words: matches.join(', ') }
+      end
+      record.errors.add(:base, I18n.t(key, translation_args))
+    end
+  end
+end

spec/models/topic_spec.rb

@@ -86,6 +86,22 @@ describe Topic do
           end
         end
       end
+
+      describe 'blocked words' do
+        describe 'when title contains watched words' do
+          it 'should not be valid' do
+            Fabricate(:watched_word, word: 'pineapple', action: WatchedWord.actions[:block])
+
+            topic.title = 'pen PinEapple apple pen is a complete sentence'
+
+            expect(topic).to_not be_valid
+
+            expect(topic.errors.full_messages.first).to include(I18n.t(
+              'contains_blocked_word', word: 'PinEapple'
+            ))
+          end
+        end
+      end
     end
   end