refactor observers. Added BaseObserver with helper methods

app/observers/base_observer.rb

+class BaseObserver < ActiveRecord::Observer
+  protected
+
+  def notification
+    NotificationService.new
+  end
+
+  def log_info message
+    Gitlab::AppLogger.info message
+  end
+end

app/observers/issue_observer.rb

-class IssueObserver < ActiveRecord::Observer
+class IssueObserver < BaseObserver
   cattr_accessor :current_user
 
   def after_create(issue)
@@ -27,8 +27,4 @@ class IssueObserver < ActiveRecord::Observer
   def create_note(issue)
     Note.create_status_change_note(issue, current_user, issue.state)
   end
-
-  def notification
-    NotificationService.new
-  end
 end

app/observers/key_observer.rb

-class KeyObserver < ActiveRecord::Observer
-  include Gitlab::ShellAdapter
-
+class KeyObserver < BaseObserver
   def after_save(key)
     GitlabShellWorker.perform_async(
       :add_key,
@@ -8,8 +6,7 @@ class KeyObserver < ActiveRecord::Observer
       key.key
     )
 
-    # Notify about ssh key being added
-    NotificationService.new.new_key(key)
+    notification.new_key(key)
   end
 
   def after_destroy(key)

app/observers/merge_request_observer.rb

-class MergeRequestObserver < ActiveRecord::Observer
+class MergeRequestObserver < BaseObserver
   cattr_accessor :current_user
 
   def after_create(merge_request)
@@ -16,10 +16,4 @@ class MergeRequestObserver < ActiveRecord::Observer
   def after_update(merge_request)
     notification.reassigned_merge_request(merge_request) if merge_request.is_being_reassigned?
   end
-
-  protected
-
-  def notification
-    NotificationService.new
-  end
 end

app/observers/note_observer.rb

-class NoteObserver < ActiveRecord::Observer
+class NoteObserver < BaseObserver
   def after_create(note)
     notification.new_note(note)
   end
-
-  protected
-
-  def notification
-    NotificationService.new
-  end
 end

app/observers/project_observer.rb

-class ProjectObserver < ActiveRecord::Observer
+class ProjectObserver < BaseObserver
   def after_create(project)
     GitlabShellWorker.perform_async(
       :add_repository,
@@ -27,10 +27,4 @@ class ProjectObserver < ActiveRecord::Observer
 
     log_info("Project \"#{project.name}\" was removed")
   end
-
-  protected
-
-  def log_info message
-    Gitlab::AppLogger.info message
-  end
 end

app/observers/system_hook_observer.rb

-class SystemHookObserver < ActiveRecord::Observer
+class SystemHookObserver < BaseObserver
   observe :user, :project, :users_project
 
   def after_create(model)

app/observers/user_observer.rb

-class UserObserver < ActiveRecord::Observer
+class UserObserver < BaseObserver
   def after_create(user)
     log_info("User \"#{user.name}\" (#{user.email}) was created")
 
@@ -18,14 +18,4 @@ class UserObserver < ActiveRecord::Observer
       end
     end
   end
-
-  protected
-
-  def log_info message
-    Gitlab::AppLogger.info message
-  end
-
-  def notification
-    NotificationService.new
-  end
 end

app/observers/users_project_observer.rb

-class UsersProjectObserver < ActiveRecord::Observer
+class UsersProjectObserver < BaseObserver
   def after_commit(users_project)
     return if users_project.destroyed?
-    Notify.delay.project_access_granted_email(users_project.id)
   end
 
   def after_create(users_project)
@@ -10,6 +9,12 @@ class UsersProjectObserver < ActiveRecord::Observer
       action: Event::JOINED,
       author_id: users_project.user.id
     )
+
+    notification.new_team_member(users_project)
+  end
+
+  def after_update(users_project)
+    notification.update_team_member(users_project)
   end
 
   def after_destroy(users_project)