#215 テスト・ケース追加

backend/app/controllers/tags_controller.rb

@@ -26,7 +26,11 @@ class TagsController < ApplicationController
 
   def show
     tag = Tag.find_by(id: params[:id])
-    render json: tag.as_json(only: [:id, :category, :post_count], methods: [:name, :has_wiki])
+    if tag
+      render json: tag.as_json(only: [:id, :category, :post_count], methods: [:name, :has_wiki])
+    else
+      head :not_found
+    end
   end
 
   def show_by_name