data-structures/tests/RedBlackTree.spec.coffee

JavaScript data structures written in CoffeeScript.

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

# Shorthand for logging tree
l = (x) -> console.log require('util').inspect(x, true, 1024)

fill = (rbt) ->
  ###
        8
    3               13
  1       6       10       14
    4       7
  ###
  rbt.add 8
  rbt.add 3
  rbt.add 10
  rbt.add 1
  rbt.add 6
  rbt.add 14
  rbt.add 4
  rbt.add 7
  rbt.add 13

Queue = require('../').Queue
validate = (rbt, treeStructure) ->
  validNodeIndex = 0
  treeQueue = new Queue([rbt._root])
  while treeQueue.size isnt 0
    currentNode = treeQueue.dequeue()
    expect(currentNode.value).toBe treeStructure[validNodeIndex]
    if currentNode._left?
      treeQueue.enqueue currentNode._left
    if currentNode._right?
      treeQueue.enqueue currentNode._right
    validNodeIndex++
  expect(validNodeIndex).toBe treeStructure.length

describe "Creation", ->
  rbt = new RedBlackTree()
  it "should be empty at the beginning", ->
    expect(rbt.size).toBe 0
  rbt2 = new RedBlackTree([8, 3, 10, 1, 6])
  it "should initialize a tree with the array passed", ->
    validate rbt2, [8, 3, 10, 1, 6]

describe "Add", ->
  rbt = new RedBlackTree()
  it "should reject undefined and null", ->
    expect(rbt.add undefined).toBeUndefined()
    expect(rbt.add null).toBeUndefined()
    expect(rbt.size).toBe 0
  it "should return the node value", ->
    expect(rbt.add 1).toBe 1
    expect(rbt.add "item").toBe "item"
  rbt2 = new RedBlackTree()
  it "should add the first node as the root", ->
    rbt2.add 8
    validate rbt2, [8]
  # The next few cases are manually checked. validate doesn't tell about
  # position. Could improve validate by making it accept a more concise
  # structure as parameter, but so far the models degrade readability.
  it "should add a node as left child of root", ->
    rbt2.add 3
    expect(rbt2._root._left.value).toBe 3
    expect(rbt2._root._left._parent.value).toBe 8
  it "should add a node as right child of root", ->
    rbt2.add 10
    expect(rbt2._root._right.value).toBe 10
    expect(rbt2._root._right._parent.value).toBe 8
  it "should add 6 as 3's right child", ->
    rbt2.add 6
    expect(rbt2._root._left._right.value).toBe 6
    expect(rbt2._root._left._right._parent.value).toBe 3
  it "should add 14 as 10's right child", ->
    rbt2.add 14
    expect(rbt2._root._right._right.value).toBe 14
    expect(rbt2._root._right._right._parent.value).toBe 10
  it "should add 4 as 8's left child and rearrange 3 to be 4's left child and 6
      to be 4's right child", ->
    rbt2.add 4
    expect(rbt2._root._left.value).toBe 4
    expect(rbt2._root._left._left.value).toBe 3
    expect(rbt2._root._left._right.value).toBe 6
  it "should add 13 as 8's child child and rearrange 10 to be 13's left child
      and 14 to be 13's right child", ->
    rbt2.add 13
    expect(rbt2._root._right.value).toBe 13
    expect(rbt2._root._right._left.value).toBe 10
    expect(rbt2._root._right._right.value).toBe 14
  it "should add 7 as 6's right child", ->
    rbt2.add 7
    expect(rbt2._root._left._right._right.value).toBe 7
    expect(rbt2._root._left._right._right._parent.value).toBe 6
  it "should add 1 as 3's left child", ->
    rbt2.add 1
    expect(rbt2._root._left._left._left.value).toBe 1
    expect(rbt2._root._left._left._left._parent.value).toBe 3
  it "shouldn't accept duplicates and return undefined", ->
    rbt2.add 1
    rbt2.add 7
    rbt2.add 6
    rbt2.add 14
    rbt2.add 3
    rbt2.add 13
    rbt2.add 8
    rbt2.add 4
    rbt2.add 10
    validate rbt2, [8, 4, 13, 3, 6, 10, 14, 1, 7]

describe "Find", ->
  rbt = new RedBlackTree()
  it "should return nothing in an empty tree", ->
    expect(rbt.has 1).toBeFalsy()
    expect(rbt.has undefined).toBeFalsy()
  it "should return a node if it's found", ->
    fill rbt
    rbt.add 1
    expect(rbt.has 1).toBeTruthy()
    rbt.add 7
    expect(rbt.has 7).toBeTruthy()
    rbt.add 6
    expect(rbt.has 6).toBeTruthy()
    rbt.add 14
    expect(rbt.has 14).toBeTruthy()
    rbt.add 3
    expect(rbt.has 3).toBeTruthy()
    rbt.add 13
    expect(rbt.has 13).toBeTruthy()
    rbt.add 8
    expect(rbt.has 8).toBeTruthy()
    rbt.add 4
    expect(rbt.has 4).toBeTruthy()
    rbt.add 10
    expect(rbt.has 10).toBeTruthy()

describe "Peek minimum", ->
  rbt = new RedBlackTree()
  it "should return undefined if the tree's empty", ->
    expect(rbt.peekMin()).toBeUndefined()
  rbt2 = new RedBlackTree()
  it "should return the node if there's only one", ->
    rbt2.add 1
    expect(rbt2.peekMin()).toBe 1
  it "should return the minimum but does not remove it", ->
    fill rbt
    expect(rbt.peekMin()).toBe 1
    expect(rbt.peekMin()).toBe 1

describe "Peek maximum", ->
  rbt = new RedBlackTree()
  it "should return undefined if the tree's empty", ->
    expect(rbt.peekMax()).toBeUndefined()
  rbt2 = new RedBlackTree()
  it "should return the node if there's only one", ->
    rbt2.add 1
    expect(rbt2.peekMin()).toBe 1
  it "should return the maximum but does not remove it", ->
    fill rbt
    expect(rbt.peekMax()).toBe 14
    expect(rbt.peekMax()).toBe 14

describe "Remove", ->
  rbt = new RedBlackTree()
  it "should return undefined for deleting in an empty tree", ->
    expect(rbt.remove "hello").toBeUndefined()
    expect(rbt.remove undefined).toBeUndefined()
  it "should return undefined for deleting a non-existent value", ->
    fill rbt
    validate rbt, [8, 3, 13, 1, 6, 10, 14, 4, 7]
    expect(rbt.remove "hello").toBeUndefined()
    expect(rbt.remove undefined).toBeUndefined()
    expect(rbt.remove -1).toBeUndefined()
  it "should return the removed value", ->
    expect(rbt.remove 8).toBe 8
    expect(rbt.remove 3).toBe 3
    expect(rbt.remove 10).toBe 10
    expect(rbt.remove 1).toBe 1
  it "should have removed correctly", ->
    validate rbt, [13, 4, 14, 6, 7]
  it "should be empty after removing everything", ->
    rbt.remove 14
    rbt.remove 6
    rbt.remove 4
    rbt.remove 7
    rbt.remove 13

describe "Remove minimum", ->
  rbt = new RedBlackTree()
  it "returns undefined when tree's empty", ->
    expect(rbt.removeMin()).toBeUndefined()
  it "returns the smallest value", ->
    fill rbt
    expect(rbt.removeMin()).toBe 1
    expect(rbt.removeMin()).toBe 3
    expect(rbt.removeMin()).toBe 4
    expect(rbt.removeMin()).toBe 6
    expect(rbt.removeMin()).toBe 7
    expect(rbt.removeMin()).toBe 8
    expect(rbt.removeMin()).toBe 10
    expect(rbt.removeMin()).toBe 13
    expect(rbt.removeMin()).toBe 14
  it "should return undefined for a newly emptied tree", ->
    expect(rbt.removeMin()).toBeUndefined()

describe "Remove maximum", ->
  rbt = new RedBlackTree()
  it "returns undefined when tree's empty", ->
    expect(rbt.removeMin()).toBeUndefined()
  it "returns the biggest value", ->
    fill rbt
    expect(rbt.removeMax()).toBe 14
    expect(rbt.removeMax()).toBe 13
    expect(rbt.removeMax()).toBe 10
    expect(rbt.removeMax()).toBe 8
    expect(rbt.removeMax()).toBe 7
    expect(rbt.removeMax()).toBe 6
    expect(rbt.removeMax()).toBe 4
    expect(rbt.removeMax()).toBe 3
    expect(rbt.removeMax()).toBe 1
  it "should return undefined for a newly emptied tree", ->
    expect(rbt.removeMin()).toBeUndefined()

describe "Randomized tests", ->
  for i in [0..10]
    rbt = new RedBlackTree()
    items = []
    for i in [0...Math.random() * 30]
      item = Math.random() * 9999 - 5000
      items.push item
      rbt.add item
    for item in items
      expect(rbt.remove item).toBe item
      expect(rbt.has item).toBeFalsy()
      # Might have some random undefined value internally.
      expect(rbt.has undefined).toBeFalsy()
    expect(rbt._root).toBeUndefined()