Rename cache_* methods to preload_* in controller concern (#30209)

spec/controllers/concerns/preloading_concern_spec.rb

@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe PreloadingConcern do
+  controller(ApplicationController) do
+    include PreloadingConcern
+
+    def empty_array
+      render plain: preload_collection([], Status).size
+    end
+
+    def empty_relation
+      render plain: preload_collection(Status.none, Status).size
+    end
+
+    def account_statuses_favourites
+      render plain: preload_collection(Status.where(account_id: params[:id]), Status).map(&:favourites_count)
+    end
+  end
+
+  before do
+    routes.draw do
+      get 'empty_array' => 'anonymous#empty_array'
+      get 'empty_relation' => 'anonymous#empty_relation'
+      get 'account_statuses_favourites' => 'anonymous#account_statuses_favourites'
+    end
+  end
+
+  describe '#preload_collection' do
+    context 'when given an empty array' do
+      it 'returns an empty array' do
+        get :empty_array
+        expect(response.body).to eq '0'
+      end
+    end
+
+    context 'when given an empty relation' do
+      it 'returns an empty array' do
+        get :empty_relation
+        expect(response.body).to eq '0'
+      end
+    end
+
+    context 'when given a collection of statuses' do
+      let!(:account) { Fabricate(:account) }
+      let!(:status)  { Fabricate(:status, account: account) }
+
+      it 'correctly updates with new interactions' do
+        get :account_statuses_favourites, params: { id: account.id }
+        expect(response.body).to eq '[0]'
+
+        FavouriteService.new.call(account, status)
+
+        get :account_statuses_favourites, params: { id: account.id }
+        expect(response.body).to eq '[1]'
+      end
+    end
+  end
+end