为什么我在通过 mochai 和 chai 测试时抛出错误测试失败？ [复制]

Question

我想测试一个函数在遇到某些情况时是否会抛出错误，但是它总是测试失败（第一个），但是当我写一个简单的测试（第二个）时，它通过了，为什么？

要测试的功能

export function add(numbers){
    let nums = numbers.split(",")
    let temp = 0
    for (let num of nums) {
        num = parseInt(num)
        if (num < 0) {
            throw new Error("negative not allowed")
        }
        temp += num
    }
    return temp;
}

这是测试

import chai from "chai"
import {add} from "../try"

let expect = chai.expect
let should = chai.should()

describe("about the error throwing case", function(){
    it("should throw an error when get a negative number", function(){
        expect(add("-1,2,3")).to.throw("negative not allowed")
    })

    it("should pass the throw-error test", function(){
        (function(){throw new Error("i am an error")}).should.throw("i am an error")
        expect(function(){throw new Error("i am an error")}).to.throw("i am an error")    
    })
})

结果

./node_modules/mocha/bin/mocha test/testtry.js --require babel-register -u tdd --reporter spec



  about the error throwing case
    1) should throw an error when get a negative number
    ✓ should pass the throw-error test


  1 passing (18ms)
  1 failing

  1) about the error throwing case should throw an error when get a negative number:
     Error: negative not allowed
      at add (try.js:7:19)
      at Context.<anonymous> (test/testtry.js:9:16)

为什么以及如何解决它？谢谢

Answer 1

您应该将函数传递给expect()，而不是函数调用：

expect(function() {add("-1,2,3")}).to.throw("negative not allowed")