Extracting duplicate logic (#16035)

Prior to this commit, we had two places that need to know the nuances
ofquerying for tag flares and what we should include in our queries for
serialization.

With this commit, we're factoring towards a common source of knowledge
and providing a much needed test for the expected output of this
serialization.

Loosely related to #15916, #15983, #15994, and #16032.

app/serializers/homepage/article_serializer.rb

@@ -1,5 +1,22 @@
 module Homepage
   class ArticleSerializer < ApplicationSerializer
+    # @param relation [ActiveRecord::Relation<Article>]
+    #
+    # @return [Hash]
+    def self.serialized_collection_from(relation:)
+      # Unfortunately the FlareTag class sends one SQL query per each article,
+      # as we want to optimize by loading them in one query, we're using a different class
+      tag_flares = Homepage::FetchTagFlares.call(relation)
+
+      # including user and organization as the last step as they are not needed
+      # by the query that fetches tag flares, they are only needed by the serializer
+      relation = relation.includes(:user, :organization)
+
+      new(relation, params: { tag_flares: tag_flares }, is_collection: true)
+        .serializable_hash[:data]
+        .pluck(:attributes)
+    end
+
     attributes(
       :class_name,
       :cloudinary_video_url,

app/services/homepage/fetch_articles.rb

@@ -31,19 +31,7 @@ module Homepage
         per_page: per_page,
       )
 
-      # Unfortunately the FlareTag class sends one SQL query per each article,
-      # as we want to optimize by loading them in one query, we're using a different class
-      tag_flares = Homepage::FetchTagFlares.call(articles)
-
-      # including user and organization as the last step as they are not needed
-      # by the query that fetches tag flares, they are only needed by the serializer
-      # NOTE: wish there was a way to specify which columns to fetch for `User` and `Organization`...
-      articles = articles.includes(:user, :organization)
-
-      Homepage::ArticleSerializer
-        .new(articles, params: { tag_flares: tag_flares }, is_collection: true)
-        .serializable_hash[:data]
-        .pluck(:attributes)
+      Homepage::ArticleSerializer.serialized_collection_from(relation: articles)
     end
   end
 end

app/services/search/article.rb

@@ -16,13 +16,7 @@ module Search
 
       relation = sort(relation, term, sort_by, sort_direction)
 
-      tag_flares = Homepage::FetchTagFlares.call(relation)
-
-      # including user and organization as the last step as they are not needed
-      # by the query that fetches tag flares, they are only needed by the serializer
-      relation = relation.includes(:user, :organization)
-
-      serialize(relation, tag_flares)
+      Homepage::ArticleSerializer.serialized_collection_from(relation: relation)
     end
 
     def self.sort(relation, term, sort_by, sort_direction)
@@ -34,13 +28,5 @@ module Search
       relation.reorder(DEFAULT_SORT_BY)
     end
     private_class_method :sort
-
-    def self.serialize(articles, tag_flares)
-      Homepage::ArticleSerializer
-        .new(articles, params: { tag_flares: tag_flares }, is_collection: true)
-        .serializable_hash[:data]
-        .pluck(:attributes)
-    end
-    private_class_method :serialize
   end
 end

spec/serializers/homepage/article_serializer_spec.rb

@@ -0,0 +1,20 @@
+require "rails_helper"
+
+RSpec.describe Homepage::ArticleSerializer, type: :serializer do
+  describe "#serialized_collection_from" do
+    let(:user) { create(:user, name: "\"Rowdy\" Roddy Piper \\:/") }
+    let(:organization) { create(:organization) }
+    let(:tag) { create(:tag, name: "ama", bg_color_hex: "#f3f3f3", text_color_hex: "#cccccc") }
+    let(:article) { create(:article, user: user, organization: organization, tags: tag.name) }
+
+    before do
+      article
+      stub_const("FlareTag::FLARE_TAG_IDS_HASH", { "ama" => tag.id })
+    end
+
+    it "is parseable as JSON (once converted to_json)" do
+      response = described_class.serialized_collection_from(relation: Article.all)
+      expect(JSON.parse(response.to_json)[0].dig("user", "name")).to eq(user.name)
+    end
+  end
+end

spec/services/homepage/fetch_articles_spec.rb

@@ -4,10 +4,10 @@ RSpec.describe Homepage::FetchArticles, type: :service do
   describe ".call" do
     # rubocop:disable RSpec/ExampleLength
     it "returns results in the correct format", :aggregate_failures do
-      article = create(
-        :article, video_thumbnail_url: "https://example.com", tags: Constants::Tags::FLARE_TAG_NAMES.first
-      )
-      create(:comment, commentable: article)
+      tag = create(:tag, name: "ama", bg_color_hex: "#f3f3f3", text_color_hex: "#cccccc")
+      article = create(:article, video_thumbnail_url: "https://example.com", tags: tag.name)
+
+      stub_const("FlareTag::FLARE_TAG_IDS_HASH", { "ama" => tag.id })
 
       result = described_class.call.first