Do not generate test/helpers directory for api apps

railties/lib/rails/generators/rails/app/app_generator.rb

@@ -268,6 +268,7 @@ module Rails
       def delete_app_helpers_if_api_option
         if options[:api]
           remove_dir 'app/helpers'
+          remove_dir 'test/helpers'
         end
       end
 

railties/test/generators/api_app_generator_test.rb

@@ -81,6 +81,7 @@ class ApiAppGeneratorTest < Rails::Generators::TestCase
        config/initializers/cookies_serializer.rb
        config/initializers/session_store.rb
        vendor/assets
+       test/helpers
        tmp/cache/assets)
   end
 end