为什么我的 Mocha 测试（异步/等待）通过但同时抛出错误？答案

【问题标题】：Why my Mocha tests (Async/Await) passes but throw an error at the same time?为什么我的 Mocha 测试（异步/等待）通过但同时抛出错误？
【发布时间】：2019-12-16 00:36:46
【问题描述】：

我是 Mocha 的新手，我一直在努力测试一个使用 Web 服务生成的令牌的函数。测试通过，但最后抛出错误。问题似乎与 Async/Await 函数有关。

如果我注释掉 .end 函数，则测试通过。调试我可以看到 res.status 是 500，这意味着 await 不起作用...

我的测试文件代码如下：

var supertest = require("supertest");
var should = require("should");
const getToken = require("./getToken");

var server = supertest.agent("http://localhost:3000");

// Testing alarmStatusController
//  

describe("Get Alarm Status", () => {

    it("should return a json file and 200 if token valid", async () => {
        let token = await getToken.getValidToken();
        server
            .get("/api/node/path")
            .set('Authorization', 'Bearer ' + token)
            .expect("Content-type", /json/)
            .expect(200)
            .end(function (err, res) {

                res.status.should.equal(200);
                res.body.message.should.equal('Alarms fetched successfully');

            });
    });

});

测试结果是：

Get Alarm Status
     √ should return a json file and 200 if token valid (38ms)

    1 passing (38ms)


C:\Dev\Globalwatch3\WebServices\GlobalwatchApi\node_modules\should\cjs\should.js:254
  throw new AssertionError(params);
  ^
AssertionError: expected 500 to be 200
at Assertion.fail (C:\Dev\Globalwatch3\WebServices\GlobalwatchApi\node_modules\should\cjs\should.js:275:17)
at Assertion.value (C:\Dev\Globalwatch3\WebServices\GlobalwatchApi\node_modules\should\cjs\should.js:356:19)
at Test.<anonymous> (C:\Dev\Globalwatch3\WebServices\GlobalwatchApi\test\alarmStatus_test.js:29:39)
at Test.assert (C:\Dev\Globalwatch3\WebServices\GlobalwatchApi\node_modules\supertest\lib\test.js:181:6)
at localAssert (C:\Dev\Globalwatch3\WebServices\GlobalwatchApi\node_modules\supertest\lib\test.js:131:12)
at C:\Dev\Globalwatch3\WebServices\GlobalwatchApi\node_modules\supertest\lib\test.js:128:5
at Test.Request.callback (C:\Dev\Globalwatch3\WebServices\GlobalwatchApi\node_modules\superagent\lib\node\index.js:728:3)
at parser (C:\Dev\Globalwatch3\WebServices\GlobalwatchApi\node_modules\superagent\lib\node\index.js:916:18)
at IncomingMessage.res.on (C:\Dev\Globalwatch3\WebServices\GlobalwatchApi\node_modules\superagent\lib\node\parsers\json.js:19:7)
at IncomingMessage.emit (events.js:203:15)
at endReadableNT (_stream_readable.js:1129:12)
at process._tickCallback (internal/process/next_tick.js:63:19)

希望有人可以帮助... 谢谢

【问题讨论】：

server.end 是与callback 的异步函数。因此，您的测试用例在您致电server.end 后结束，而不是等待它完成。您需要在测试中使用done。

标签： node.js async-await mocha.js

【解决方案1】：

你可以使用 Promise 代替 end 回调：

const supertest = require("supertest");
const should = require("should");
const getToken = require("./getToken");
const server = supertest.agent("http://localhost:3000");

describe("Get Alarm Status", () => {

    it("should return a json file and 200 if token valid", async () => {
        let token = await getToken.getValidToken();

        const res = await server
            .get("/api/node/path")
            .set('Authorization', 'Bearer ' + token)
            .expect("Content-type", /json/)
            .expect(200);

        res.status.should.equal(200);
        res.body.message.should.equal('Alarms fetched successfully');
    });

});

【讨论】：