A Ruby implementation of a Binary Search Algorithm

binary_search.rb

require 'test/unit'

module Search
    extend self

    def binary(container, item)
        _binary container, item, 0, container.length
    end

    def _binary(container, item, min, max)
        return nil if container.empty?

        mid = midpoint min, max

        if container[mid] > item
            return _binary(container, item, min, mid - 1)
        elsif container[mid] < item
            return _binary(container, item, mid + 1, max)
        else
            return mid
        end
    end

    def midpoint(min, max)
        min + ((max - min) / 2)
    end
end

if __FILE__ == $0
    class TestBinarysearch < Test::Unit::TestCase
        def test_bsearch
            elements = [1, 3, 4, 6, 8, 9, 11]

            assert_equal 2, Search.binary(elements, 4) 
            assert_equal 5, Search.binary(elements, 9)
        end
    end
end