require 'test/unit'
require 'full_adder_rules0.rb'

class FARulesTest < Test::Unit::TestCase

  def test_FA_rules_000
    s = simulate_full_adder('000')
    assert_equal('00', s)
  end

  def test_FA_rules_001
    s = simulate_full_adder('001')
    assert_equal('10', s)
  end

  def test_FA_rules_010
    s = simulate_full_adder('010')
    assert_equal('10', s)
  end

  def test_FA_rules_011
    s = simulate_full_adder('011')
    assert_equal('01', s)
  end

  def test_FA_rules_100
    s = simulate_full_adder('100')
    assert_equal('10', s)
  end

  def test_FA_rules_101
    s = simulate_full_adder('101')
    assert_equal('01', s)
  end

  def test_FA_rules_110
    s = simulate_full_adder('110')
    assert_equal('01', s)
  end

  def test_FA_rules_111
    s = simulate_full_adder('111')
    assert_equal('11', s)
  end

  def test_FA_rules_non_binary
    d = gen_random_bad_3string()
    puts "\nBad:" + d  #write it out for curiosity
    s = simulate_full_adder(d)		#error case
    assert_equal('unrecognized digits', s)
  end

  def test_FA_rules_length0
    s = simulate_full_adder('')	#error case
    assert_equal('illegal length', s)
  end

  def test_FA_rules_length1
    s = simulate_full_adder('0')	#error case
    assert_equal('illegal length', s)
  end

  def test_FA_rules_length2
    s = simulate_full_adder('00')	#error case
    assert_equal('illegal length', s)
  end

  def test_FA_rules_length4
    s = simulate_full_adder('0000')	#error case
    assert_equal('illegal length', s)
  end

  #Helper method to generate a string of length 3
  #that contains at least one char that is not a 0 or 1.
  #Used to generate error strings for test_FA_rules_non_binary.
  def gen_random_bad_3string()
    begin
        threechr = []
        threechr << (rand(95)+32).chr << (rand(95)+32).chr << (rand(95)+32).chr
    end while (threechr - ["0","1"]).length == 0
    return threechr.to_s	#convert the array into a string and return it
  end

end