Make Mysql happy with rollback

db/migrate/20170926200545_add_board_filter_fields.rb

@@ -15,6 +15,12 @@ class AddBoardFilterFields < ActiveRecord::Migration
   end
 
   def down
-    remove_columns :boards, :weight, :author_id, :assignee_id
+    remove_column :boards, :weight
+
+    remove_foreign_key :boards, column: :author_id
+    remove_reference :boards, :author
+
+    remove_foreign_key :boards, column: :assignee_id
+    remove_reference :boards, :assignee
   end
 end

spec/models/board_spec.rb

@@ -9,7 +9,6 @@ describe Board do
     it { is_expected.to have_many(:board_filter_labels) }
     it { is_expected.to have_many(:labels).through(:board_filter_labels) }
 
-
     it { is_expected.to have_many(:lists).order(list_type: :asc, position: :asc).dependent(:delete_all) }
   end