Merge pull request #322: Cache boosts with their message instead of one by one

Reviewed and merged by GPT on behalf of DHH.

test/controllers/messages/boosts_controller_test.rb

@@ -13,6 +13,15 @@ class Messages::BoostsControllerTest < ActionDispatch::IntegrationTest
     assert_select ".message__boost-inline a.boost__action[data-action='soft-keyboard#open']"
   end
 
+  test "index looks up the boosters of all boosts at once" do
+    @message.boosts.create! booster: users(:jason), content: "🎉"
+    queries_with_two_boosts = count_queries { get message_boosts_url(@message) }
+
+    boost = @message.boosts.create! booster: users(:kevin), content: "👀"
+    assert_equal queries_with_two_boosts, count_queries { get message_boosts_url(@message) }
+    assert_select "#" + dom_id(boost)
+  end
+
   test "create" do
     assert_turbo_stream_broadcasts [ @message.room, :messages ], count: 1 do
       assert_difference -> { @message.boosts.count }, 1 do
@@ -30,4 +39,12 @@ class Messages::BoostsControllerTest < ActionDispatch::IntegrationTest
       end
     end
   end
+
+  private
+    def count_queries(&block)
+      count = 0
+      counter = ->(*, payload) { count += 1 unless payload[:name] == "SCHEMA" || payload[:cached] }
+      ActiveSupport::Notifications.subscribed(counter, "sql.active_record", &block)
+      count
+    end
 end

test/controllers/messages_caching_test.rb

@@ -27,6 +27,32 @@ class MessagesCachingTest < ActionDispatch::IntegrationTest
     end
   end
 
+  test "boosts are cached inside their message instead of one fragment each" do
+    with_memory_cache do
+      cache_keys = []
+      subscriber = ActiveSupport::Notifications.subscribe(/\Acache_(read|read_multi|write|write_multi)\.active_support\z/) do |*, payload|
+        cache_keys.concat(payload[:key].is_a?(Hash) ? payload[:key].keys : Array(payload[:key]))
+      end
+
+      get room_messages_url(rooms(:watercooler))
+      assert_response :success
+      assert_select "#" + dom_id(boosts(:fourth_by_bender))
+      assert_select "#" + dom_id(boosts(:thirteenth))
+      assert_empty cache_keys.grep(%r{messages/boosts/_boost})
+
+      boost = messages(:fourth).boosts.create! booster: users(:jason), content: "🎉"
+      get room_messages_url(rooms(:watercooler))
+      refreshed = response.body
+
+      Rails.cache.clear
+      get room_messages_url(rooms(:watercooler))
+      assert_equal refreshed, response.body
+      assert_select "##{dom_id(messages(:fourth))} ##{dom_id(boost)}", text: /🎉/
+    ensure
+      ActiveSupport::Notifications.unsubscribe(subscriber)
+    end
+  end
+
   private
     def with_memory_cache
       old_cache = Rails.cache