 
       it 'should contains clone of parents if not enough probability', ->
         pair.crossover 0, ->
-          assert.false
+          throw new AssertionError 'crossover operator should not call'
 
         expect pair.offsprings
           .to.be.a 'array'

        .to.deep.equal [1, 1, 1, 1]
      expect offspring.fitness()
        .to.equal 4

'use strict'
{expect,AssertionError} = require 'chai'

describe 'Individual.pair', ->
  Popuration = require '../lib/popuration'
