linked_list.rb

class Node
  attr_accessor :value, :next_node_in_stack

  def initialize(value, next_node_in_stack)
    @value = value
    @next_node_in_stack = next_node_in_stack
  end
end

class LinkedList
  attr_accessor :head, :tail

  def initialize(head, tail)
    @head = nil
    @tail = head
  end

  def add(value)
    @added = Node.new(value, @head)
    @added.next = @head
    @head = @added
  end

  def remove(value)
    return nil if empty?
    value = @head.value
    @head = @head.next
    puts value
  end

  def find(value)
    return self if @value == value
  end

  def tail
    if empty?
      return nil
    end
  end

  def length
  end
end

=begin
  ############################
  RSPEC CONFIG AND TESTS BELOW
  ############################
=end

RSpec.configure do |config|
  config.failure_color = :magenta
  config.tty = true
  config.color = true
  config.default_formatter = 'doc'
end

describe LinkedList do
  it "has a head" do
    ll = LinkedList.new
    expect(ll.head).to be_nil
    ll.add(1)
    expect(ll.head.value).to eql(1)
  end

  it "has a tail" do
    ll = LinkedList.new
    ll.add(1)
    expect(ll.tail.value).to eql(1)
    ll.add(2)
    expect(ll.tail.value).to eql(2)
    expect(ll.tail.next_node).to be_nil
  end

  it "adds a value" do
    ll = LinkedList.new
    ll.add(1)
    ll.add(2)
    ll.add(3)
    expect(ll.head.value).to eql(1)
    expect(ll.tail.value).to eql(3)
  end

  it "finds a node" do
    ll = LinkedList.new
    10.times do |i|
      ll.add(i)
    end
    node_4 =  ll.find(4)
    expect(node_4.value).to eql(4)
    node_5 =  ll.find(5)
    expect(node_5.value).to eql(5)
  end

  it "removes a node" do
    ll = LinkedList.new
    10.times do |i|
      ll.add(i)
    end
    node_4 =  ll.find(4)
    expect(node_4.next_node.value).to eql(5)
    ll.remove(5)
    expect(node_4.next_node.value).to eql(6)
  end

  it "has a length" do
    ll = LinkedList.new
    expect(ll.length).to eql(0)

    ll.add("thefirst")
    expect(ll.length).to eql(1)

    10.times do |i|
      ll.add(i)
    end
    expect(ll.length).to eql(11)
  end
end