Refactor note awards to reuse `emoji_pattern` and improve validator

app/models/note.rb

@@ -39,9 +39,11 @@ class Note < ActiveRecord::Base
   delegate :name, to: :project, prefix: true
   delegate :name, :email, to: :author, prefix: true
 
+  before_validation :set_award!
+
   validates :note, :project, presence: true
   validates :note, uniqueness: { scope: [:author, :noteable_type, :noteable_id] }, if: ->(n) { n.is_award }
-  validates :note, format: { with: /\A[-_+[:alnum:]]*\z/ }, if: -> (n){ n.is_award }
+  validates :note, inclusion: { in: Emoji.emojis_names }, if: ->(n) { n.is_award }
   validates :line_code, format: { with: /\A[a-z0-9]+_\d+_\d+\Z/ }, allow_blank: true
   # Attachments are deprecated and are handled by Markdown uploader
   validates :attachment, file_size: { maximum: :max_attachment_size }
@@ -72,7 +74,6 @@ class Note < ActiveRecord::Base
 
   serialize :st_diff
   before_create :set_diff, if: ->(n) { n.line_code.present? }
-  before_validation :set_award!
 
   class << self
     def discussions_from_notes(notes)
@@ -351,36 +352,31 @@ class Note < ActiveRecord::Base
     !system?
   end
 
-  # Checks if note is an award added from an issue comment.
+  # Checks if note is an award added as a comment
   #
-  # If note is an award, this method sets is_award to true,
-  # and changes note content to award-emoji name.
-  #
-  # Awards are only supported for issue comments.
+  # If note is an award, this method sets is_award to true
+  #   and changes content of the note to award name.
   #
   # Method is executed as a before_validation callback.
   #
   def set_award!
-    return unless supports_awards? && contains_emoji_only?
-
+    return unless awards_supported? && contains_emoji_only?
     self.is_award = true
     self.note = award_emoji_name
   end
 
-  def supports_awards?
-    noteable.kind_of?(Issue) ||
-      noteable.is_a?(MergeRequest)
-  end
-
   private
 
+  def awards_supported?
+    noteable.kind_of?(Issue) || noteable.is_a?(MergeRequest)
+  end
+
   def contains_emoji_only?
-    (note =~ /\A:[-_+[:alnum:]]*:\s?\z/) ? true : false
+    emoji_only_pattern = /\A#{Gitlab::Markdown::EmojiFilter.emoji_pattern}\s?\Z/
+    (note =~ emoji_only_pattern) ? true : false
   end
 
   def award_emoji_name
-    return nil unless contains_emoji_only?
-
-    note.match(/\A:([-_+[:alnum:]]*):\s?/)[1]
+    note.match(Gitlab::Markdown::EmojiFilter.emoji_pattern)[1]
   end
 end