Chop

Chop.rb

# http://codekata.pragprog.com/2007/01/kata_two_karate.html
class Chop
  def chop(int, ar)
    return -1 unless ar.include?(int)
    return ar.index(int)
  end
end

TC_Chop.rb

require 'test/unit'
require './Chop'

class TestChop < Test::Unit::TestCase
  def setup
    @chop = Chop.new
  end

  def teardown
    @chop = nil
  end

  def test_chop
    assert_equal(-1, @chop.chop(0, [1, 2, 3]))
    assert_equal(0, @chop.chop(1, [1, 2, 3]))
    assert_equal(2, @chop.chop(3, [1, 2, 3]))
    #
    assert_equal(0,  @chop.chop(1, [1, 3, 5]))
    assert_equal(1,  @chop.chop(3, [1, 3, 5]))
    assert_equal(2,  @chop.chop(5, [1, 3, 5]))
    assert_equal(-1, @chop.chop(0, [1, 3, 5]))
    assert_equal(-1, @chop.chop(2, [1, 3, 5]))
    assert_equal(-1, @chop.chop(4, [1, 3, 5]))
    assert_equal(-1, @chop.chop(6, [1, 3, 5]))
    #
    assert_equal(0,  @chop.chop(1, [1, 3, 5, 7]))
    assert_equal(1,  @chop.chop(3, [1, 3, 5, 7]))
    assert_equal(2,  @chop.chop(5, [1, 3, 5, 7]))
    assert_equal(3,  @chop.chop(7, [1, 3, 5, 7]))
    assert_equal(-1, @chop.chop(0, [1, 3, 5, 7]))
    assert_equal(-1, @chop.chop(2, [1, 3, 5, 7]))
    assert_equal(-1, @chop.chop(4, [1, 3, 5, 7]))
    assert_equal(-1, @chop.chop(6, [1, 3, 5, 7]))
    assert_equal(-1, @chop.chop(8, [1, 3, 5, 7]))
  end
end