1 files changed, 58 insertions, 0 deletions
diff --git a/railties/test/application/initializers/notifications_test.rb b/railties/test/application/initializers/notifications_test.rb
new file mode 100644
index 0000000000..c65c955734
--- /dev/null
+++ b/railties/test/application/initializers/notifications_test.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require "isolation/abstract_unit"
+
+module ApplicationTests
+  class NotificationsTest < ActiveSupport::TestCase
+    include ActiveSupport::Testing::Isolation
+
+    def setup
+      build_app
+    end
+
+    def teardown
+      teardown_app
+    end
+
+    def instrument(*args, &block)
+      ActiveSupport::Notifications.instrument(*args, &block)
+    end
+
+    def wait
+      ActiveSupport::Notifications.notifier.wait
+    end
+
+    test "rails log_subscribers are added" do
+      add_to_config <<-RUBY
+        config.colorize_logging = false
+      RUBY
+
+      require "#{app_path}/config/environment"
+      require "active_support/log_subscriber/test_helper"
+
+      logger = ActiveSupport::LogSubscriber::TestHelper::MockLogger.new
+      ActiveRecord::Base.logger = logger
+      ActiveRecord::Base.verbose_query_logs = false
+
+      # Mimic Active Record notifications
+      instrument "sql.active_record", name: "SQL", sql: "SHOW tables"
+      wait
+
+      assert_equal 1, logger.logged(:debug).size
+      assert_match(/SHOW tables/, logger.logged(:debug).last)
+    end
+
+    test "rails load_config_initializer event is instrumented" do
+      app_file "config/initializers/foo.rb", ""
+
+      events = []
+      callback = ->(*_) { events << _ }
+      ActiveSupport::Notifications.subscribed(callback, "load_config_initializer.railties") do
+        app
+      end
+
+      assert_equal %w[load_config_initializer.railties], events.map(&:first)
+      assert_includes events.first.last[:initializer], "config/initializers/foo.rb"
+    end
+  end
+end