diff --git a/db/migrate/20111211233957_add_comment_count_to_action_tracker.rb b/db/migrate/20111211233957_add_comment_count_to_action_tracker.rb
index 80b68c8..67ee22a 100644
--- a/db/migrate/20111211233957_add_comment_count_to_action_tracker.rb
+++ b/db/migrate/20111211233957_add_comment_count_to_action_tracker.rb
@@ -4,6 +4,6 @@ class AddCommentCountToActionTracker < ActiveRecord::Migration
   end
 
   def self.down
-    remove_column :action_tracker, :comments_count, :integer, :default => 0
+    remove_column :action_tracker, :comments_count, :integer
   end
 end
diff --git a/db/migrate/20120228154642_add_visibility_to_action_tracker.rb b/db/migrate/20120228154642_add_visibility_to_action_tracker.rb
new file mode 100644
index 0000000..ce87899
--- /dev/null
+++ b/db/migrate/20120228154642_add_visibility_to_action_tracker.rb
@@ -0,0 +1,9 @@
+class AddVisibilityToActionTracker < ActiveRecord::Migration
+  def self.up
+    add_column :action_tracker, :visible, :boolean, :default => true
+  end
+
+  def self.down
+    remove_column :action_tracker, :visible, :boolean
+  end
+end
diff --git a/test/unit/comment_test.rb b/test/unit/comment_test.rb
index d7ff6b2..3e33172 100644
--- a/test/unit/comment_test.rb
+++ b/test/unit/comment_test.rb
@@ -331,4 +331,5 @@ class CommentTest < ActiveSupport::TestCase
 
   should 'update article activity when add a comment'
   should 'update activity when add a comment'
+  should 'create a new activity when add a comment and the activity was removed'
 end
--
libgit2 0.21.2