adding gemfile.lock
add debugger gem
add rspec-its
add first tests for standard cheeses
setup specific items for test
quality degrades twice as fast when expired
test that quality never goes below zero
add tests for aged brie
test for when aged brie is expired
added tests for sulfuras
add tests for backstage
replace strings with constants
introduce reduce quality method
use reduce_quality method
extract increase_quality method and replace usages
extract zero_out_quality method
extract reduce_sell_in method
extract methods quality_above and quality_below
refactor for loop to be ruby each construct
make if blocks more explicit for type