Everlane Problem

everlane.rb

def everlane(string)
  new_string = string.gsub(/[bcdefghij]/, "a").gsub(/[MKP]/, "Q")
  test_array = []
  array = new_string.split(//)
  status = "VALID"
  
  array.length.times do
     current_letter = array.pop
     case current_letter
     when "a"
       if test_array.length > 1
         status = "INVALID"
       else
         test_array << "a"
       end
     when "Z"
       if test_array.length == 0
         status = "INVALID"
       else 
         test_array << "Z" + test_array.pop
       end
     when "Q"
       if test_array.length < 2
         status = "INVALID"
       else
         test_array << "Q" + test_array.pop + test_array.pop
       end
     else
       status = "INVALID"
     end
  end

  if test_array.length != 1
    status = "INVALID"
  end

puts "#{string} #{status}"
end

everlane("QaZZc")