module RangeSpecs class TenfoldSucc include Comparable attr_reader :n def initialize(n) @n = n end def <=>(other) @n <=> other.n end def succ self.class.new(@n * 10) end end # Custom Range classes Xs and Ys class Custom include Comparable attr_reader :length def initialize(n) @length = n end def eql?(other) inspect.eql? other.inspect end alias :== :eql? def inspect 'custom' end def <=>(other) @length <=> other.length end end class Xs < Custom # represent a string of 'x's def succ Xs.new(@length + 1) end def inspect 'x' * @length end end class Ys < Custom # represent a string of 'y's def succ Ys.new(@length + 1) end def inspect 'y' * @length end end class MyRange < Range end class ComparisonError < RuntimeError end end