"commented on your answer"

app/models/comment.rb

@@ -5,4 +5,8 @@ class Comment < ActiveRecord::Base
   validates :answer_id, presence: true
 
   validates :content, length: { maximum: 160 }
+
+  def notification_type(*_args)
+    Notifications::Commented
+  end
 end

app/models/notifications/commented.rb

@@ -0,0 +1,2 @@
+class Notifications::Commented < Notification
+end

app/models/user.rb

@@ -108,7 +108,8 @@ class User < ActiveRecord::Base
   end
 
   def comment(answer, content)
-    Comment.create!(user: self, answer: answer, content: content)
+    comment = Comment.create!(user: self, answer: answer, content: content)
+    Notification.notify answer.user, comment unless answer.user == self
     increment! :commented_count
     answer.increment! :comment_count
   end

app/views/notifications/index.html.haml

@@ -46,16 +46,17 @@
                     ago
                   .notification--icon
                     %i.fa.fa-smile-o
-      %li.list-group-item
-        .media
-          .pull-left
-            %img.notification--img
-          .media-body
-            %h6.media-heading.notification--user
-              username
-            %p.notification--text
-              commented
-              %a your answer
-              some time ago!
-            .notification--icon
-              %i.fa.fa-comments
+              - when "Comment"
+                .pull-left
+                  %img.notification--img{src: gravatar_url(notification.target.user)}
+                .media-body
+                  %h6.media-heading.notification--user
+                    = user_screen_name notification.target.user
+                  %p.notification--text
+                    commented on
+                    %a{href: show_user_answer_path(username: notification.target.user.screen_name, id: notification.target.answer.id)}
+                      %a your answer
+                    = time_ago_in_words notification.target.created_at
+                    ago
+                  .notification--icon
+                    %i.fa.fa-comments