Fix ・ detection in hashtag regex to construct hashtag correctly (#22888)

* Fix ・ detection in hashtag regex to construct hashtag correctly

* Fixed rubocop liniting issues

* More rubocop linting fix

app/models/tag.rb

@@ -26,8 +26,12 @@ class Tag < ApplicationRecord
   has_many :featured_tags, dependent: :destroy, inverse_of: :tag
   has_many :followers, through: :passive_relationships, source: :account
 
-  HASHTAG_SEPARATORS = "_\u00B7\u200c"
-  HASHTAG_NAME_PAT = "([[:word:]_][[:word:]#{HASHTAG_SEPARATORS}]*[[:alpha:]#{HASHTAG_SEPARATORS}][[:word:]#{HASHTAG_SEPARATORS}]*[[:word:]_])|([[:word:]_]*[[:alpha:]][[:word:]_]*)"
+  HASHTAG_SEPARATORS = "_\u00B7\u30FB\u200c"
+  HASHTAG_FIRST_SEQUENCE_CHUNK_ONE = "[[:word:]_][[:word:]#{HASHTAG_SEPARATORS}]*[[:alpha:]#{HASHTAG_SEPARATORS}]"
+  HASHTAG_FIRST_SEQUENCE_CHUNK_TWO = "[[:word:]#{HASHTAG_SEPARATORS}]*[[:word:]_]"
+  HASHTAG_FIRST_SEQUENCE = "(#{HASHTAG_FIRST_SEQUENCE_CHUNK_ONE}#{HASHTAG_FIRST_SEQUENCE_CHUNK_TWO})"
+  HASTAG_LAST_SEQUENCE = '([[:word:]_]*[[:alpha:]][[:word:]_]*)'
+  HASHTAG_NAME_PAT = "#{HASHTAG_FIRST_SEQUENCE}|#{HASTAG_LAST_SEQUENCE}"
 
   HASHTAG_RE = /(?:^|[^\/\)\w])#(#{HASHTAG_NAME_PAT})/i
   HASHTAG_NAME_RE = /\A(#{HASHTAG_NAME_PAT})\z/i
@@ -45,7 +49,11 @@ class Tag < ApplicationRecord
   scope :listable, -> { where(listable: [true, nil]) }
   scope :trendable, -> { Setting.trendable_by_default ? where(trendable: [true, nil]) : where(trendable: true) }
   scope :not_trendable, -> { where(trendable: false) }
-  scope :recently_used, ->(account) { joins(:statuses).where(statuses: { id: account.statuses.select(:id).limit(1000) }).group(:id).order(Arel.sql('count(*) desc')) }
+  scope :recently_used, ->(account) {
+                          joins(:statuses)
+                            .where(statuses: { id: account.statuses.select(:id).limit(1000) })
+                            .group(:id).order(Arel.sql('count(*) desc'))
+                        }
   scope :matches_name, ->(term) { where(arel_table[:name].lower.matches(arel_table.lower("#{sanitize_sql_like(Tag.normalize(term))}%"), nil, true)) } # Search with case-sensitive to use B-tree index
 
   update_index('tags', :self)
@@ -105,7 +113,8 @@ class Tag < ApplicationRecord
       names = Array(name_or_names).map { |str| [normalize(str), str] }.uniq(&:first)
 
       names.map do |(normalized_name, display_name)|
-        tag = matching_name(normalized_name).first || create(name: normalized_name, display_name: display_name.gsub(HASHTAG_INVALID_CHARS_RE, ''))
+        tag = matching_name(normalized_name).first || create(name: normalized_name,
+                                                             display_name: display_name.gsub(HASHTAG_INVALID_CHARS_RE, ''))
 
         yield tag if block_given?
 
@@ -154,6 +163,9 @@ class Tag < ApplicationRecord
   end
 
   def validate_display_name_change
-    errors.add(:display_name, I18n.t('tags.does_not_match_previous_name')) unless HashtagNormalizer.new.normalize(display_name).casecmp(name.mb_chars).zero?
+    unless HashtagNormalizer.new.normalize(display_name).casecmp(name.mb_chars).zero?
+      errors.add(:display_name,
+                 I18n.t('tags.does_not_match_previous_name'))
+    end
   end
 end

spec/models/tag_spec.rb

+# frozen_string_literal: true
 require 'rails_helper'
 
-RSpec.describe Tag, type: :model do
+RSpec.describe Tag do
   describe 'validations' do
     it 'invalid with #' do
-      expect(Tag.new(name: '#hello_world')).to_not be_valid
+      expect(described_class.new(name: '#hello_world')).not_to be_valid
     end
 
     it 'invalid with .' do
-      expect(Tag.new(name: '.abcdef123')).to_not be_valid
+      expect(described_class.new(name: '.abcdef123')).not_to be_valid
     end
 
     it 'invalid with spaces' do
-      expect(Tag.new(name: 'hello world')).to_not be_valid
+      expect(described_class.new(name: 'hello world')).not_to be_valid
     end
 
     it 'valid with ａｅｓｔｈｅｔｉｃ' do
-      expect(Tag.new(name: 'ａｅｓｔｈｅｔｉｃ')).to be_valid
+      expect(described_class.new(name: 'ａｅｓｔｈｅｔｉｃ')).to be_valid
     end
   end
 
@@ -62,6 +63,10 @@ RSpec.describe Tag, type: :model do
       expect(subject.match('hello #one·two·three').to_s).to eq ' #one·two·three'
     end
 
+    it 'matches ・unicode in ぼっち・ざ・ろっく correctly' do
+      expect(subject.match('testing #ぼっち・ざ・ろっく').to_s).to eq ' #ぼっち・ざ・ろっく'
+    end
+
     it 'matches ZWNJ' do
       expect(subject.match('just add #نرم‌افزار and').to_s).to eq ' #نرم‌افزار'
     end
@@ -89,44 +94,46 @@ RSpec.describe Tag, type: :model do
   describe '.find_normalized' do
     it 'returns tag for a multibyte case-insensitive name' do
       upcase_string   = 'abcABCａｂｃＡＢＣやゆよ'
-      downcase_string = 'abcabcａｂｃａｂｃやゆよ';
+      downcase_string = 'abcabcａｂｃａｂｃやゆよ'
 
       tag = Fabricate(:tag, name: HashtagNormalizer.new.normalize(downcase_string))
-      expect(Tag.find_normalized(upcase_string)).to eq tag
+      expect(described_class.find_normalized(upcase_string)).to eq tag
     end
   end
 
   describe '.matches_name' do
     it 'returns tags for multibyte case-insensitive names' do
       upcase_string   = 'abcABCａｂｃＡＢＣやゆよ'
-      downcase_string = 'abcabcａｂｃａｂｃやゆよ';
+      downcase_string = 'abcabcａｂｃａｂｃやゆよ'
 
       tag = Fabricate(:tag, name: HashtagNormalizer.new.normalize(downcase_string))
-      expect(Tag.matches_name(upcase_string)).to eq [tag]
+      expect(described_class.matches_name(upcase_string)).to eq [tag]
     end
 
     it 'uses the LIKE operator' do
-      expect(Tag.matches_name('100%abc').to_sql).to eq %q[SELECT "tags".* FROM "tags" WHERE LOWER("tags"."name") LIKE LOWER('100abc%')]
+      result = %q[SELECT "tags".* FROM "tags" WHERE LOWER("tags"."name") LIKE LOWER('100abc%')]
+      expect(described_class.matches_name('100%abc').to_sql).to eq result
     end
   end
 
   describe '.matching_name' do
     it 'returns tags for multibyte case-insensitive names' do
       upcase_string   = 'abcABCａｂｃＡＢＣやゆよ'
-      downcase_string = 'abcabcａｂｃａｂｃやゆよ';
+      downcase_string = 'abcabcａｂｃａｂｃやゆよ'
 
       tag = Fabricate(:tag, name: HashtagNormalizer.new.normalize(downcase_string))
-      expect(Tag.matching_name(upcase_string)).to eq [tag]
+      expect(described_class.matching_name(upcase_string)).to eq [tag]
     end
   end
 
   describe '.find_or_create_by_names' do
+    let(:upcase_string) { 'abcABCａｂｃＡＢＣやゆよ' }
+    let(:downcase_string) { 'abcabcａｂｃａｂｃやゆよ' }
+
     it 'runs a passed block once per tag regardless of duplicates' do
-      upcase_string   = 'abcABCａｂｃＡＢＣやゆよ'
-      downcase_string = 'abcabcａｂｃａｂｃやゆよ';
-      count           = 0
+      count = 0
 
-      Tag.find_or_create_by_names([upcase_string, downcase_string]) do |tag|
+      described_class.find_or_create_by_names([upcase_string, downcase_string]) do |_tag|
         count += 1
       end
 
@@ -136,28 +143,28 @@ RSpec.describe Tag, type: :model do
 
   describe '.search_for' do
     it 'finds tag records with matching names' do
-      tag = Fabricate(:tag, name: "match")
-      _miss_tag = Fabricate(:tag, name: "miss")
+      tag = Fabricate(:tag, name: 'match')
+      _miss_tag = Fabricate(:tag, name: 'miss')
 
-      results = Tag.search_for("match")
+      results = described_class.search_for('match')
 
       expect(results).to eq [tag]
     end
 
     it 'finds tag records in case insensitive' do
-      tag = Fabricate(:tag, name: "MATCH")
-      _miss_tag = Fabricate(:tag, name: "miss")
+      tag = Fabricate(:tag, name: 'MATCH')
+      _miss_tag = Fabricate(:tag, name: 'miss')
 
-      results = Tag.search_for("match")
+      results = described_class.search_for('match')
 
       expect(results).to eq [tag]
     end
 
     it 'finds the exact matching tag as the first item' do
-      similar_tag = Fabricate(:tag, name: "matchlater", reviewed_at: Time.now.utc)
-      tag = Fabricate(:tag, name: "match", reviewed_at: Time.now.utc)
+      similar_tag = Fabricate(:tag, name: 'matchlater', reviewed_at: Time.now.utc)
+      tag = Fabricate(:tag, name: 'match', reviewed_at: Time.now.utc)
 
-      results = Tag.search_for("match")
+      results = described_class.search_for('match')
 
       expect(results).to eq [tag, similar_tag]
     end