FIX: include children categories when searching a category

lib/search.rb

@@ -665,7 +665,8 @@ class Search
           end
 
         elsif @search_context.is_a?(Category)
-          posts = posts.where("topics.category_id = #{@search_context.id}")
+          category_ids = [@search_context.id] + Category.where(parent_category_id: @search_context.id).pluck(:id)
+          posts = posts.where("topics.category_id in (?)", category_ids)
         elsif @search_context.is_a?(Topic)
           posts = posts.where("topics.id = #{@search_context.id}")
                        .order("posts.post_number")

spec/components/search_spec.rb

@@ -397,12 +397,17 @@ describe Search do
       topic = Fabricate(:topic, category: category)
       topic_no_cat = Fabricate(:topic)
 
+      # includes subcategory in search
+      subcategory = Fabricate(:category, parent_category_id: category.id)
+      sub_topic = Fabricate(:topic, category: subcategory)
+
       post = Fabricate(:post, topic: topic, user: topic.user )
       _another_post = Fabricate(:post, topic: topic_no_cat, user: topic.user )
+      sub_post = Fabricate(:post, raw: 'I am saying hello from a subcategory', topic: sub_topic, user: topic.user )
 
       search = Search.execute('hello', search_context: category)
-      expect(search.posts.length).to eq(1)
-      expect(search.posts.first.id).to eq(post.id)
+      expect(search.posts.map(&:id).sort).to eq([post.id,sub_post.id].sort)
+      expect(search.posts.length).to eq(2)
     end
 
   end