Chai

Question

我对 Chai 很陌生，所以我仍然在掌握一些东西。

我已经编写了函数来检查 API 响应和 return 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了测试，但是，我在错误测试方面遇到了困难。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，我得到以下错误信息：

1) networkDataHelper #formatPostcodeStatus a request with an incorrect postcode throws an error: Error: INVALID_POSTCODE

似乎抛出的错误导致测试失败，但我不太确定。有人有什么想法吗？

Answer 1

请注意，我不是 Chai 专家，您拥有的构造：

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

不可能在 Chai 框架开始查看您的 .to.throw() 链之前处理抛出的异常。上面的代码调用函数在调用 expect() 之前，所以异常发生得太快了。

相反，您应该将函数传递给 expect():

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

这样，框架可以在为异常准备好后调用函数。

Chai - 期望函数抛出错误

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javascript