require "isolation/abstract_unit" module ApplicationTests class InitializerTest < Test::Unit::TestCase include ActiveSupport::Testing::Isolation def setup build_app boot_rails end test "initializers only ever run once" do class MyApp < Rails::Application initializer :counter do $counter += 1 end end $counter = 0 MyApp.initializers[:counter].run MyApp.initializers[:counter].run assert_equal 1, $counter end end end