linked_list.rb

require "test/unit"

class ListTester < Test::Unit::TestCase
  def test_node_integrity
    node = Node.new(1)
    assert_equal(1,node.value)
    assert_equal(nil,node.next_node)
    assert_equal(nil,node.previous_node)
  end

  def test_list_creation
    list = LinkedList.new()
    assert_equal(list.root,nil)
  end

  def test_list_integrity
    list = LinkedList.new
    # tests a blank list
    assert_equal(list.root,nil)
    assert_equal(list.current_node,nil)
    # tests list with one integer element
    list.push_to(1)
    assert_equal(list.root.value,1)
    assert_equal(list.current_node.value,1)
    # tests list with object as a value
    list = LinkedList.new
    node = Node.new(1)
    list.push_to(node)
    assert_equal(list.root.value,node)
    assert_equal(list.current_node.value,node)
  end

  def test_adds_node_with_root
    node1 = Node.new(1)
    list = LinkedList.new(node1)

    assert_equal(list.root.value,1)
    list.push_to(2)
    assert_equal(list.root.next_node.value, 2)
    list.push_to(3)
    assert_equal(list.current_node.value, 3)
    list.push_to(4)
    assert_equal(list.current_node.value, 4)

    assert_equal(list.length, 4)
  end

  def test_adds_node_without_root
    list = LinkedList.new()

    list.push_to(1)
    assert_equal(list.root.value,1)
    list.push_to(2)
    assert_equal(list.root.next_node.value, 2)
    list.push_to(3)
    assert_equal(list.current_node.value, 3)
    list.push_to(4)
    assert_equal(list.current_node.value, 4)

    assert_equal(list.length, 4)
  end

  # def test_present?
  #   list = LinkedList.new()
  #   list.push_to(1)
  #   list.push_to(2)
  #   list.push_to(3)
  #   list.push_to(4)
  #   assert_equal(list.present?(1, list.current_node), true)
  #   assert_equal(list.present?(2, list.current_node), true)
  #   assert_equal(list.present?(3, list.current_node), true)
  #   assert_equal(list.present?(4, list.current_node), true)
  # end

  # def test_delete
  #   list = LinkedList.new()
  #   list.push_to(1)
  #   list.push_to(2)
  #   list.push_to(3)
  #   list.push_to(4)
  #   assert_equal(list.present?(2),true)
  #   list.delete(2)
  #   assert_equal(list.present?(2),false)
  # end

end

class LinkedList
  attr_accessor :root, :length, :current_node
  def initialize(root=nil)
    @root = root
    @root.nil? ? @length = 0 : @length = 1
    @current_node = root
  end

  def progress_node
    @current_node = @current_node.next_node
  end

  def push_to(value)
    if @root==nil
      @root = Node.new(value)
      @current_node = root
    else
      new_node = Node.new(value)
      @current_node.next_node = new_node
      progress_node
    end
    @length += 1
  end

  def present?(value, node)
    if node.value == value && node.next_node != nil
      return true
    else
      progress_node
      present?(value, @current_node)
    end
  end

  def go_to(value)
    place = 0
    until place == value
      progress_node
      place += 1
    end
    return @current_node
  end

  def delete(value)

  end

  def list
    if @root.next_node != nil
      p @root.value
      @root = @root.next_node
    else
      p "end"
    end
  end
end

class Node
  attr_accessor :value, :next_node, :previous_node
  def initialize(value=nil)
    @value = value
    @next_node = nil
    @previous_node = nil
  end
end