jgn

def assert_equality(example, actual, expected)
  print "example #{example}: "
  if actual == expected
    puts 'Pass'
  else
    puts "Fail: got #{actual.inspect}; expected #{expected.inspect}"
  end
end

examples = [

jgn

class HalfAdder
  attr_reader :sum, :carry

  def initialize(augend, addend)
    @augend, @addend = augend, addend
  end

  def compute
  end
end

jgn

example [0, 0, 0, 0]: Fail: got nil; expected 0
example [0, 0, 0, 0]: Fail: got nil; expected 0
example [1, 0, 0, 1]: Fail: got nil; expected 0
example [1, 0, 0, 1]: Fail: got nil; expected 1
example [0, 1, 0, 1]: Fail: got nil; expected 0
example [0, 1, 0, 1]: Fail: got nil; expected 1
example [1, 1, 1, 0]: Fail: got nil; expected 1
example [1, 1, 1, 0]: Fail: got nil; expected 0

jgn

class HalfAdder
  attr_reader :sum, :carry

  def initialize(augend, addend)
    @augend, @addend = augend, addend
  end

  def compute
    @carry = @augend & @addend
    @sum = @augend ^ @addend

jgn

class HalfAdder
  attr_reader :sum, :carry

  def initialize(augend, addend, logger)
    @augend, @addend, @logger = augend, addend, logger
  end

  def compute
    @carry = @augend & @addend
    @sum = @augend ^ @addend

jgn

class HalfAdder
  attr_reader :sum, :carry

  def initialize(augend, addend, logger)
    @augend, @addend, @logger = augend, addend, logger
  end

  def compute
    @carry = @augend & @addend
    @sum = @augend ^ @addend

jgn

class Logger
  attr_reader :log_output
  def info(s)
    @log_output ||= ""
    @log_output << s << "\n"
  end
end

examples.each do |example|
  a, b, c, s = example

jgn

require 'logger'
def get_logger
  logger = Logger.new(STDOUT)
  def logger.info(s)
    @log_output ||= ""
    @log_output << s << "\n"
  end
  def logger.log_output
    @log_output
  end

jgn

class UnexpectedOutputError < StandardError; end
class MockLogger
  def initialize(expected_indirect_outputs)
    @eio = Array(expected_indirect_outputs)
  end
  def info(s)
    expected = @eio.shift
    if expected != s
      raise UnexpectedOutputError.new("Fail: got #{s}; expected #{expected}")
    end

jgn

#!/usr/bin/env ruby
# http://en.wikipedia.org/wiki/RADIX-50
class String
  R50_CHARS = " ABCDEFGHIJKLMNOPQRSTUVWXYZ$.%0123456789"
  R50_LOOKUP = {}.tap { |h| String::R50_CHARS.split(//).each_with_index { |c, i| h[c] = i } }
  R50_CLEAN = /[[:upper:]|[:digit:]| |.|$|%]/
  def radix50
    [].tap do |r|
      self.upcase.scan(R50_CLEAN).inject([]) do |m, c|
        m << R50_LOOKUP[c]