Jasmine custom class Test

SetClass.coffee

class Set
    set = {}
    col = []

    has: (item) ->
        set.hasOwnProperty item

    refresh: (item, opt_) ->
        col = Object.keys set

    valueOf: ->
        col

    add: (item, opt_) ->
        if !@has item
            set[item] ?= opt_ ? true
            @refresh(item, opt_)
        else
            @valueOf()

    del: (item) ->
       if @has item
            delete set[item];
       @valueOf()

    size: ->
        col.length

describe "Set", ->
    set = null
    it "Its initialization should return an object", ->
        expect(set = new Set()).toEqual(jasmine.any Object)

    describe "Definition", ->
        it "class should be defined", ->
            expect(Set).toBeDefined()
        it "has :Add to put an item in its Set", ->
            expect(Set.prototype.add).toBeDefined()
            expect(set.add).toEqual(jasmine.any Function)
        it "has :Del to kick an item of its Set", ->
            expect(Set.prototype.del).toBeDefined()
            expect(set.del).toEqual(jasmine.any Function)
        it "has :Has to check existence of item in its Set", ->
            expect(Set.prototype.has).toBeDefined()
            expect(set.has).toEqual(jasmine.any Function)
        it "has :Size to know cardinality of the Set", ->
            expect(Set.prototype.size).toBeDefined()
            expect(set.size).toEqual(jasmine.any Function)

    describe "Add method", ->
        set = null
        beforeEach ->
            set = new Set()
        afterEach ->
            set = null

        it "stores only one item after a single item added", ->
            expect(set.add 1).toEqual ['1']
            expect(set.valueOf().length).toEqual 1

        it "stores only item after adding same item up to 99 times", ->
            for [1..Math.random()*100]
                set.add(1)
            expect(set.add(1)).toEqual ['1']
            expect(set.size()).toEqual 1
         
        it "returns an array with same cardinality as its Set", ->
            lengthTest = 1 + Math.round Math.random()*10
            set.add(item) for item in [0..lengthTest-1]
            expect(set.size()).toEqual lengthTest