why rails generator can not generate helper test automatically?

rails version: rails 4.2.5.2

test_helper.rb:

-  1 ENV['RAILS_ENV'] ||= 'test'
|  2 require File.expand_path('../../config/environment', __FILE__)
|  3 require 'rails/test_help'
|  4
-  5 # use minitest report
|  6 require 'minitest/reporters'
|  7 Minitest::Reporters.use!
|  8
-  9 class ActiveSupport::TestCase
| 10   # Setup all fixtures in test/fixtures/*.yml for all tests in alphabetical order.
| 11   fixtures :all
| 12
- 13   # Add more helper methods to be used by all tests here...
| 14 end

when i run "rails g controller HomePages "

create  app/controllers/home_pages_controller.rb
  invoke  erb
  create    app/views/home_pages
  invoke  test_unit
  create    test/controllers/home_pages_controller_test.rb
  invoke  helper
  create    app/helpers/home_pages_helper.rb
  invoke    test_unit
  invoke  assets
  invoke    coffee
  create      app/assets/javascripts/home_pages.coffee
  invoke    scss
  create      app/assets/stylesheets/home_pages.scss

Obviously,it didn't generate helper unit test automatically.

So, i have to create this file by myself.

How can i solve this problem? Thank you.