Allow groups to be mentioned.

Resolves #1673.

app/controllers/projects_controller.rb

@@ -102,7 +102,7 @@ class ProjectsController < ApplicationController
     note_type = params['type']
     note_id = params['type_id']
     autocomplete = ::Projects::AutocompleteService.new(@project)
-    participants = ::Projects::ParticipantsService.new(@project).execute(note_type, note_id)
+    participants = ::Projects::ParticipantsService.new(@project, current_user).execute(note_type, note_id)
 
     @suggestions = {
       emojis: autocomplete_emojis,

app/models/concerns/mentionable.rb

@@ -51,9 +51,12 @@ module Mentionable
       identifier = match.delete "@"
       if identifier == "all"
         users.push(*project.team.members.flatten)
+      elsif namespace = Namespace.find_by(path: identifier)
+        if namespace.type == "Group"
+          users.push(*namespace.users)
         else
-        id = User.find_by(username: identifier).try(:id)
-        users << User.find(id) unless id.blank?
+          users << namespace.owner
+        end
       end
     end
     users.uniq

app/services/projects/participants_service.rb

 module Projects
   class ParticipantsService < BaseService
-    def initialize(project)
+    def initialize(project, user)
       @project  = project
+      @user     = user
     end
 
     def execute(note_type, note_id)
@@ -12,7 +13,7 @@ module Projects
           []
         end
       team_members = sorted(@project.team.members)
-      participants = all_members + team_members + participating
+      participants = all_members + groups + team_members + participating
       participants.uniq
     end
 
@@ -37,6 +38,10 @@ module Projects
       users.uniq.to_a.compact.sort_by(&:username).map { |user| { username: user.username, name: user.name } }
     end
 
+    def groups
+      @user.authorized_groups.sort_by(&:path).map { |group| { username: group.path, name: group.name } }
+    end
+
     def all_members
       [{ username: "all", name: "Project and Group Members" }]
     end

doc/markdown/markdown.md

@@ -170,7 +170,7 @@ GFM will turn that reference into a link so you can navigate between them easily
 
 GFM will recognize the following:
 
-- @foo : for team members
+- @foo : for specific team members or groups
 - @all : for the whole team
 - #123 : for issues
 - !123 : for merge requests

lib/gitlab/markdown.rb

@@ -202,8 +202,15 @@ module Gitlab
 
       if identifier == "all"
         link_to("@all", project_url(project), options)
-      elsif User.find_by(username: identifier)
-        link_to("@#{identifier}", user_url(identifier), options)
+      elsif namespace = Namespace.find_by(path: identifier)
+        url =
+          if namespace.type == "Group"
+            group_url(identifier)
+          else 
+            user_url(identifier)
+          end
+          
+        link_to("@#{identifier}", url, options)
       end
     end