April Fools' 2025: Randomly lie about .nil? to make a ruby program undebuggable

bogus_nil.rb

#!/usr/bin/ruby
# A Mean Ruby trick for April Fools
#
# This is why code review is important.
module NilTracer
  def self.included(base)
    base.class_eval do
      alias_method :original_nil?, :nil?

      def nil?
        if rand(3) == 0
          return (not original_nil?)
        end

        original_nil?
      end
    end
  end
end

Object.include(NilTracer)
NilClass.include(NilTracer)

puts "5 is never nil"
x = 5
10.times { || puts x.nil? }

puts "nil is always nil"
x = nil
10.times { || puts x.nil? }