Chai - 期望函数抛出错误

Question

我对Chai很新,所以我仍然要掌握一切.

我编写的函数将检查API响应并返回正确的消息或抛出错误.

networkDataHelper.prototype.formatPostcodeStatus = function(postcodeStatus) {

if (postcodeStatus.hasOwnProperty("errorCode")) {
    //errorCode should always be "INVALID_POSTCODE"
    throw Error(postcodeStatus.errorCode);
}

if (postcodeStatus.hasOwnProperty("lori")) {
    return "There appears to be a problem in your area. " + postcodeStatus.lori.message;
}

else if (postcodeStatus.maintenance !== null) {
    return postcodeStatus.maintenance.bodytext;
}

else {
    return "There are currently no outages in your area.";
}
};

我已经设法为消息传递编写测试,但是,我正在努力进行错误测试.这是我迄今为止所写的内容:

var networkDataHelper = require('../network_data_helper.js');

describe('networkDataHelper', function() {
var subject = new networkDataHelper();
var postcode;

    describe('#formatPostcodeStatus', function() {
        var status = {
            "locationValue":"SL66DY",
            "error":false,
            "maintenance":null,
        };

        context('a request with an incorrect postcode', function() {
            it('throws an error', function() {
                status.errorCode = "INVALID_POSTCODE";
                expect(subject.formatPostcodeStatus(status)).to.throw(Error);
            });
        });
    });
});

当我运行上面的测试时,我收到以下错误消息:

1)networkDataHelper #formatPostcodeStatus带有错误邮政编码的请求会引发错误:错误:INVALID_POSTCODE

似乎抛出的错误导致测试失败,但我不太确定.有没有人有任何想法？

Answer 1

随着我不是柴专家的警告,你有这样的结构:

expect(subject.formatPostcodeStatus(status)).to.throw(Error);

在Chai框架到处看到你的.to.throw()链之前,不可能处理抛出的异常.上面的代码调用该函数之前的号召expect()制成,所以异常太早发生.

相反,您应该将函数传递给expect():

expect(function() { subject.formatPostCodeStatus(status); })
  .to.throw(Error);

这样,框架可以在为异常做好准备后调用该函数.