diff --git a/railties/lib/rails.rb b/railties/lib/rails.rb
index e995001725..ab389d6fc5 100644
--- a/railties/lib/rails.rb
+++ b/railties/lib/rails.rb
@@ -71,6 +71,7 @@ def root
     #   Rails.env # => "development"
     #   Rails.env.development? # => true
     #   Rails.env.production? # => false
+    #   Rails.env.local? # => true              true for "development" and "test", false for anything else
     def env
       @_env ||= ActiveSupport::EnvironmentInquirer.new(ENV["RAILS_ENV"].presence || ENV["RACK_ENV"].presence || "development")
     end