data-structures/tests/LinkedList.spec.coffee

JavaScript data structures written in CoffeeScript.

LinkedList = require('../source').LinkedList

# Shorthand for logging
l = (linkedList) ->
  output = ""
  currentNode = linkedList.head
  for i in [0...linkedList.size]
    output += currentNode.value + " "
    currentNode = currentNode.next
  console.log output

fill = (linkedList) ->
  linkedList.add 5
  linkedList.add 2
  linkedList.add 9
  linkedList.add 0
  linkedList.add 12

validate = (linkedList, nodeValues...) ->
  expect(linkedList.size).toBe nodeValues.length
  expect(linkedList.head.prev).toBeUndefined()
  expect(linkedList.tail.next).toBeUndefined()
  expect(linkedList.head.value).toBe nodeValues[0]
  expect(linkedList.tail.value).toBe nodeValues[nodeValues.length - 1]

  if nodeValues.length is 0 or nodeValues.length is 1
    expect(linkedList.head.next).toBeUndefined()
    expect(linkedList.tail.prev).toBeUndefined()

  if nodeValues.length is 1
    expect(linkedList.head).toBe linkedList.tail
  else if nodeValues.length isnt 0
    expect(linkedList.head.next.value).toBe nodeValues[1]
    expect(linkedList.tail.prev.value).toBe nodeValues[nodeValues.length - 2]

    currentNode = linkedList.head.next
    for i in [1...nodeValues.length - 1]
      expect(currentNode.value).toBe nodeValues[i]
      expect(currentNode.next.value).toBe nodeValues[i + 1]
      expect(currentNode.prev.value).toBe nodeValues[i - 1]
      currentNode = currentNode.next

describe "Create new linked list", ->
  linkedList = new LinkedList()
  it "should have all head and tail properties unitialized to undefined", ->
    validate linkedList
  linkedList2 = new LinkedList([])
  it "should create an empty list too, if the parameter passed is empty", ->
    validate linkedList2
  linkedList3 = new LinkedList([1, 2, 3, 4])
  it "should create a list prepopulated with items of the passed array", ->
    validate linkedList3, 1, 2, 3, 4

describe "Add node and check size", ->
  describe "at the end", ->
    linkedList = new LinkedList()
    it "should return the value added", ->
      expect(linkedList.add 1).toBe 1
      expect(linkedList.add null).toBeNull()
      expect(linkedList.add undefined).toBeUndefined()
      expect(linkedList.size).toBe 3
    linkedList2 = new LinkedList()
    it "should add to the head when the list's empty. It's also the tail", ->
      linkedList2.add "item0"
      validate linkedList2, "item0"
    it "should add a second item and get head and tail right", ->
      linkedList2.add "item1"
      validate linkedList2, "item0", "item1"
    it "should add items in order", ->
      fill linkedList2
      validate linkedList2, "item0", "item1", 5, 2, 9, 0, 12

  describe "using offset", ->
    linkedList = new LinkedList()
    it "should return the value added", ->
      expect(linkedList.add 1).toBe 1
      expect(linkedList.add null).toBeNull()
      expect(linkedList.add undefined).toBeUndefined()
    linkedList2 = new LinkedList()
    it "should insert a new first item correctly", ->
      linkedList2.add 9, 0
      linkedList2.add 10, 0
      validate linkedList2, 10, 9
    it "should add more items in the correct order", ->
      linkedList2.add 99, 2
      linkedList2.add 2, 3
      linkedList2.add "hi", 3
      linkedList2.add null, 0
      linkedList2.add "orange", 5
      linkedList2.add undefined, 7
      validate linkedList2, null, 10, 9, 99, "hi", "orange", 2, undefined
    linkedList3 = new LinkedList()
    it "should return undefined and keep the list intact when the position
        parameter is invalid", ->
      expect(linkedList3.add "item", 1).toBeUndefined()
      expect(linkedList3.add "item", -1).toBeUndefined()
      expect(linkedList3.head.value).toBeUndefined()
      expect(linkedList3.tail.value).toBeUndefined()
      fill linkedList3
      expect(linkedList3.add 99, -100).toBeUndefined()
      validate linkedList3, 5, 2, 9, 0, 12
    it "should allow valid negative position index", ->
      expect(linkedList3.add "apple", -3).toBe "apple"
      linkedList3.add 12, -3
      linkedList3.add 15, 0
      linkedList3.add 88, -6
      linkedList3.add -4, -2
      validate linkedList3, 15, 5, 88, 2, "apple", 12, 9, -4, 0, 12

describe "Remove node using position", ->
  describe "from the end", ->
    linkedList = new LinkedList()
    it "should not error when removing empty linked list", ->
      expect(linkedList.removeAt()).toBeUndefined()
    linkedList2 = new LinkedList()
    it "should return the value of the removed node", ->
      fill linkedList2
      expect(linkedList2.removeAt()).toBe 12
      expect(linkedList2.removeAt()).toBe 0
      expect(linkedList2.removeAt()).toBe 9
      expect(linkedList2.removeAt()).toBe 2
      expect(linkedList2.removeAt()).toBe 5
    linkedList3 = new LinkedList()
    it "should remove node and join its sides correctly", ->
      fill linkedList3
      linkedList3.removeAt()
      validate linkedList3, 5, 2, 9, 0
      linkedList3.removeAt()
      validate linkedList3, 5, 2, 9
      linkedList3.removeAt()
      validate linkedList3, 5, 2
      linkedList3.removeAt()
      validate linkedList3, 5
      linkedList3.removeAt()
      validate linkedList3

  describe "using offset", ->
    linkedList = new LinkedList()
    it "should remove the right item", ->
      fill linkedList
      expect(linkedList.removeAt 0).toBe 5
      expect(linkedList.removeAt -1).toBe 12
      expect(linkedList.removeAt -3).toBe 2
      expect(linkedList.removeAt 1).toBe 0
      expect(linkedList.removeAt 0).toBe 9
      expect(linkedList.removeAt()).toBeUndefined()
    linkedList2 = new LinkedList()
    it "should return undefined when the remove is invalid", ->
      fill linkedList2
      expect(linkedList2.removeAt 9).toBeUndefined()
      expect(linkedList2.removeAt -100).toBeUndefined()
    it "should not modify linked list after invalid removes", ->
      validate linkedList2, 5, 2, 9, 0, 12

describe "Remove node using value", ->
  linkedList = new LinkedList()
  it "should return undefined if list's empty", ->
    expect(linkedList.remove 999).toBeUndefined()
    expect(linkedList.remove undefined).toBeUndefined()
    expect(linkedList.remove null).toBeUndefined()
  it "should return undefined if value's not found", ->
    fill linkedList
    expect(linkedList.remove 999).toBeUndefined()
    expect(linkedList.remove undefined).toBeUndefined()
    expect(linkedList.remove null).toBeUndefined()
    validate linkedList, 5, 2, 9, 0, 12
  it "should return the value removed", ->
    expect(linkedList.remove 2).toBe 2
    expect(linkedList.remove 5).toBe 5
    expect(linkedList.remove 12).toBe 12
  linkedList2 = new LinkedList()
  it "should have kept the list chained", ->
    fill linkedList2
    linkedList2.remove 5
    linkedList2.remove 12
    linkedList2.remove undefined
    linkedList2.remove 9
    validate linkedList2, 2, 0
    linkedList2.remove 0
    linkedList2.remove 2
    validate linkedList2


describe "Get node", ->
  linkedList = new LinkedList()
  it "should return undefined for invalid node", ->
    expect(linkedList.at()).toBeUndefined()
    expect(linkedList.at 0).toBeUndefined()
    fill linkedList
    expect(linkedList.at 5).toBeUndefined()
    expect(linkedList.at -6).toBeUndefined()
  it "should return the value for a valid node", ->
    expect(linkedList.at(0).value).toBe 5
    expect(linkedList.at(-5).value).toBe 5
    expect(linkedList.at(1).value).toBe 2
    expect(linkedList.at(-4).value).toBe 2
    expect(linkedList.at(2).value).toBe 9
    expect(linkedList.at(-3).value).toBe 9
    expect(linkedList.at(3).value).toBe 0
    expect(linkedList.at(-2).value).toBe 0
    expect(linkedList.at(4).value).toBe 12
    expect(linkedList.at(-1).value).toBe 12

describe "Find index of node", ->
  describe "starting at the beginning", ->
    linkedList = new LinkedList()
    array = [1, 2, 3]
    it "returns -1 if the item isn't found", ->
      linkedList.add "hello"
      linkedList.add -1
      linkedList.add [1, 2, 3]
      linkedList.add array
      linkedList.add 10
      linkedList.add 10
      linkedList.add ""
      expect(linkedList.indexOf [1, 2, 3]).toBe -1
      expect(linkedList.indexOf 99).toBe -1
    it "returns the index of the item found", ->
      expect(linkedList.indexOf "hello").toBe 0
      expect(linkedList.indexOf -1).toBe 1
      expect(linkedList.indexOf array).toBe 3
      expect(linkedList.indexOf 10).toBe 4
      expect(linkedList.indexOf "").toBe 6
    linkedList2 = new LinkedList()
    it "shouldn't find anything in an empty linked list", ->
      expect(linkedList2.indexOf "").toBe -1
      expect(linkedList2.indexOf "hello").toBe -1
    linkedList3 = new LinkedList()
    it "should find undefined and null if they're present only", ->
      expect(linkedList3.indexOf undefined).toBe -1
      expect(linkedList3.indexOf null).toBe -1
      linkedList3.add undefined
      linkedList3.add null
      expect(linkedList3.indexOf undefined).toBe 0
      expect(linkedList3.indexOf null).toBe 1
  describe "starting at an arbitrary index", ->
    linkedList = new LinkedList()
    it "should return -1 for invalid positive index", ->
      expect(linkedList.indexOf 2, 0).toBe -1
      expect(linkedList.indexOf 2, 10).toBe -1
      fill linkedList
      expect(linkedList.indexOf 2, 99).toBe -1
    it "should return the correct value for a negative index", ->
      expect(linkedList.indexOf 2, -99).toBe 1
      expect(linkedList.indexOf 0, -2).toBe 3
      linkedList.add 9
      expect(linkedList.indexOf 9, -3).toBe 5
      expect(linkedList.indexOf 9, -1).toBe 5
      expect(linkedList.indexOf 9, 0).toBe 2
    it "returns -1 if the item isn't found starting at the indicated index", ->
      expect(linkedList.indexOf 2, 2).toBe -1
      expect(linkedList.indexOf 5, 1).toBe -1
    it "returns the index of the item found", ->
      expect(linkedList.indexOf 9, 2).toBe 2
      expect(linkedList.indexOf 5, 0).toBe 0
      expect(linkedList.indexOf 12, 4).toBe 4
      expect(linkedList.indexOf 0, 1).toBe 3
    linkedList2 = new LinkedList()
    it "works with negative index", ->
      fill linkedList2
      expect(linkedList2.indexOf 9, -3).toBe 2
      expect(linkedList2.indexOf 5, -5).toBe 0
      expect(linkedList2.indexOf 12, -1).toBe 4
      expect(linkedList2.indexOf 0, -3).toBe 3