text: 'use strict'
  const {describe, it} = require('mocha')
  const {expect} = require('chai')
  
  const calculatePolish = require('../src/calculate')
  
  describe('calculatePolish', function() {
    it('should return undefined on an empty stack', () => {
      expect(calculatePolish([])).to.be.undefined
    })
  
    it('should return TOS if only numbers ', () => {
      expect(calculatePolish([3, 4, 5])).to.equal(5)
    })
  
    it('should return sum calculation', () => {
      expect(calculatePolish([3, 4, '+'])).to.equal(7)
    })
  
    it('should return diff calculation', () => {
      expect(calculatePolish([3, 4, '-'])).to.equal(-1)
    })
  
    it('should return mult calculation', () => {
      expect(calculatePolish([3, 4, '*'])).to.equal(12)
    })
  
    it('should return div calculation', () => {
      expect(calculatePolish([10, 5, '/'])).to.equal(2)
    })
  
    it('should return multiple calculations', () => {
      expect(calculatePolish([11, 5, 8, 4,  '/', '*', '+'])).to.equal(21)
    })
  })
  