Kata Two -- Karate Chop

#/usr/bin/ruby

# Write a binary chop method that takes an integer search target
# and a sorted array of integers. It should return the integer
# index of the target in the array, or -1 if the target is not
# in #the array. The signature will logically be:
#
#   chop(int, array_of_int)  -> int
# You can assume that the array has less than 100,000 elements. 
# For the purposes of this Kata, time and memory performance are 
# not issues (assuming the chop terminates before you get bored 
# and kill it, and that you have enough RAM to run it).

def chop(int, array_of_int)
  array_of_int.index int or -1
end

require 'test/unit'

class KataTwo < Test::Unit::TestCase
# This code comes from CodeKata.
# see http://codekata.pragprog.com/2007/01/kata_two_karate.html

  def test_chop
    assert_equal(-1, chop(3, []))
    assert_equal(-1, chop(3, [1]))
    assert_equal(0,  chop(1, [1]))

    assert_equal(0,  chop(1, [1, 3, 5]))
    assert_equal(1,  chop(3, [1, 3, 5]))
    assert_equal(2,  chop(5, [1, 3, 5]))
    assert_equal(-1, chop(0, [1, 3, 5]))
    assert_equal(-1, chop(2, [1, 3, 5]))
    assert_equal(-1, chop(4, [1, 3, 5]))
    assert_equal(-1, chop(6, [1, 3, 5]))

    assert_equal(0,  chop(1, [1, 3, 5, 7]))
    assert_equal(1,  chop(3, [1, 3, 5, 7]))
    assert_equal(2,  chop(5, [1, 3, 5, 7]))
    assert_equal(3,  chop(7, [1, 3, 5, 7]))
    assert_equal(-1, chop(0, [1, 3, 5, 7]))
    assert_equal(-1, chop(2, [1, 3, 5, 7]))
    assert_equal(-1, chop(4, [1, 3, 5, 7]))
    assert_equal(-1, chop(6, [1, 3, 5, 7]))
    assert_equal(-1, chop(8, [1, 3, 5, 7]))
  end
end