# File lib/pt_testcase.rb, line 197
  def self.previous(key, extra=0) # FIX: remove R2C code
    idx = @@testcase_order.index(key)

    raise "Unknown class #{key} in @@testcase_order" if idx.nil?

    case key
    when "RubyToRubyC" then
      idx -= 1
    end
    @@testcase_order[idx - 1 - extra]
  end