Linked List in Ruby

linked_list.rb

#!/usr/bin/env ruby -wKU
require "test/unit"

class LinkedList
  attr_accessor :head

  def add(value)
    if self.head.nil?
      self.head = Node.new(value)
    elsif self.head && self.head.next_node.nil?
      self.head.next_node = Node.new(value)
    else
      tmp = self.tail
      tmp.next_node = Node.new(value)
    end
  end

  def remove(value)
    tmp = self.head
    while(tmp.value != value)
      prev = tmp
      tmp = tmp.next_node
    end
    prev.next_node = tmp.next_node
    return self
  end

  def find(value)
    tmp = self.head
    while(tmp.value != value)
      tmp = tmp.next_node
    end
    return tmp
  end

  def tail
    return nil unless self.head
    tmp = self.head
    while(tmp.next_node)
      tmp = tmp.next_node
    end
    return tmp
  end

  def length
    return nil unless self.head
    tmp = self.head
    i = 0
    while(tmp.next_node)
      tmp = tmp.next_node
      i += 1
    end
    return i
  end
end

class Node
  attr_accessor :value, :next_node
  def initialize(value,next_node=nil)
    self.value = value
    self.next_node = next_node
  end
end

class TestLinkedList < Test::Unit::TestCase

  def test__value_added
    ll = LinkedList.new
    ll.add(1)
    ll.add(2)
    ll.add(3)
    assert ll.head.value.eql?(1)
    assert ll.tail.value.eql?(3)
  end

  def test__it_has_head
    ll = LinkedList.new
    assert ll.head.nil?
    ll.add(1)
    assert ll.head.value.eql?(1)
  end

  def test__it_has_tail
    ll = LinkedList.new
    ll.add(1)
    assert ll.tail.value.eql?(1)
    ll.add(2)
    assert ll.tail.value.eql?(2)
    assert ll.tail.next_node.nil?
  end

  def test__it_finds_node
    ll = LinkedList.new
    10.times do |i|
      ll.add(i)
    end
    node_4 =  ll.find(4)
    assert node_4.value.eql?(4)
    node_5 =  ll.find(5)
    assert node_5.value.eql?(5)
  end

  def test__removes_node
    ll = LinkedList.new
    10.times do |i|
      ll.add(i)
    end
    node_4 =  ll.find(4)
    assert node_4.next_node.value.eql?(5)
    ll.remove(5)
    assert node_4.next_node.value.eql?(6)
  end

  def test__it_returns_length
    ll = LinkedList.new
    10.times do |i|
      ll.add(i)
    end
    assert ll.length.eql?(9)
  end

end

LinkedListTest

$> ./linked_list.rb
Run options:

# Running tests:

......

Finished tests in 0.000599s, 10016.6945 tests/s, 20033.3890 assertions/s.

6 tests, 12 assertions, 0 failures, 0 errors, 0 skips

sliding_windows.rb

class SlidingWindow
  def self.slide_em(arr = [],window=nil)
    counter = 0
    while(counter<=arr.size)
      p arr[counter..counter+(window-1)]
      counter += 1
    end

  end
end

values = %w(1 2 3 4 5 6 7 8 9 10)

SlidingWindow.slide_em(values,3)