flatten

flatten.rb

#!/usr/bin/env ruby
# encoding: utf-8
require "test/unit"

# Flatten an array given any nesting depth
def flatten(array, result = [])
  
  return result unless array.is_a?(Array)

  array.each do |element|

    if element.is_a?(Array)
      flatten(element, result)
    else
      result << element
    end

  end

  return result

end

class TestFlatten < Test::Unit::TestCase

  def test_flatten_no_array
    source  = 1
    target = []
    assert_equal( target, flatten( source ) )
  end

  def test_flatten_no_depth
    source  = [1,2,3,4]
    target = [1,2,3,4]
    assert_equal( target, flatten( source ) )
  end

  def test_flatten
    source  = [[1,2,[3]],4]
    target = [1,2,3,4]
    assert_equal( target, flatten( source ) )
  end
 
end