Missing use Cake\View\Helper and extends from Helper

Maybe I'm wrong, but I follow the ProgressHelper Test instructions and I found 2 possible errors:

1) Line "use Cake\View\Helper;" is missing.
2) ¿Extends Helper insted of AppHelper?
Merge pull request #1933 from verzi/patch-1

Missing use Cake\View\Helper and extends from Helper
Fix formatting.