使用 Jest、Supertest、MongoDB 和 Express 进行测试时的拆卸错误

Question

我正在使用 Jest 和 Supertest 测试我的 Express 路线。在设置应用程序时，我还连接到 MongoDB 并将 MongoClient 添加到 app.locals。

我收到一个错误，当我注释掉对 MongoClient 的调用时不会发生该错误。

ReferenceError: You are trying to `import` a file after the Jest environment has been torn down.

      at BufferList.Readable (server/node_modules/readable-stream/lib/_stream_readable.js:179:22)
      at BufferList.Duplex (server/node_modules/readable-stream/lib/_stream_duplex.js:67:12)
      at new BufferList (server/node_modules/bl/bl.js:33:16)
      at new MessageStream (server/node_modules/mongodb/lib/cmap/message_stream.js:35:21)
      at new Connection (server/node_modules/mongodb/lib/cmap/connection.js:54:28)
/Users/zackchan/Documents/dev/server/node_modules/readable-stream/lib/_stream_readable.js:111
  var isDuplex = stream instanceof Duplex;
                        ^

TypeError: Right-hand side of 'instanceof' is not callable
    at new ReadableState (/Users/zackchan/Documents/dev/server/node_modules/readable-stream/lib/_stream_readable.js:111:25)
    at BufferList.Readable (/Users/zackchan/Documents/dev/server/node_modules/readable-stream/lib/_stream_readable.js:183:25)
    at BufferList.Duplex (/Users/zackchan/Documents/dev/server/node_modules/readable-stream/lib/_stream_duplex.js:67:12)
    at new BufferList (/Users/zackchan/Documents/dev/server/node_modules/bl/bl.js:33:16)
    at new MessageStream (/Users/zackchan/Documents/dev/server/node_modules/mongodb/lib/cmap/message_stream.js:35:21)
    at new Connection (/Users/zackchan/Documents/dev/server/node_modules/mongodb/lib/cmap/connection.js:54:28)
    at /Users/zackchan/Documents/dev/server/node_modules/mongodb/lib/core/connection/connect.js:36:29
    at callback (/Users/zackchan/Documents/dev/server/node_modules/mongodb/lib/core/connection/connect.js:280:5)
    at TLSSocket.connectHandler (/Users/zackchan/Documents/dev/server/node_modules/mongodb/lib/core/connection/connect.js:325:5)
    at Object.onceWrapper (events.js:421:28)

当我注释掉我的 MongoClient 调用时，我收到了这个 Jest 警告：

Jest did not exit one second after the test run has completed.
This usually means that there are asynchronous operations that weren't stopped in your tests. Consider running Jest with `--detectOpenHandles` to troubleshoot this issue.

这是我的测试脚本和应用模块

app.js

const https = require('https');
const fs = require('fs');
const path = require('path');
const dotenv = require('dotenv');
const express = require('express');
const rateLimiter = require('express-rate-limit');
const { MongoClient } = require('mongodb');

const app = express();
const port = process.env.PORT || 443;
const limit = rateLimiter({ window: 15 * 60 * 1000, max: 100 });

var httpsOptions;
if(process.env.NODE_ENV === 'development'){
    const rootCA = require('ssl-root-cas').create().addFile(path.join(__dirname, './cert/CA.pem'));
    https.globalAgent.options.ca = rootCA;
    httpsOptions = {
        key: fs.readFileSync(path.join(__dirname, './cert/localhost.key')),
        cert: fs.readFileSync(path.join(__dirname, './cert/localhost.crt'))
    };
}

MongoClient.connect(process.env.MONGODB_URI, { useNewUrlParser: true, useUnifiedTopology: true }, (err, mongoClient) => {
    if(err) throw err;
    app.locals.mongoClient = mongoClient;
});

app.use(limit);
app.use(express.json());

app.get('/', (req, res) => {
    res.json({path: '/'});
});

const server = https.createServer(httpsOptions, app).listen(port);

module.exports = app;

test.js

const dotenv = require('dotenv');
const path = require('path');
process.env = dotenv.config({path: path.resolve(__dirname, '.env')}).parsed;

const request = require('supertest');
const app = require('../app');


describe('GET /', () => {
    it('responds with path of /', (done) => {
        // app.locals is empty here
        request(app).get('/').expect(JSON.stringify({path: '/'}), done);
    });
});

我尝试在使用app.locals.mongoClient.close() 的测试用例之后关闭与MongoDB 的连接，但mongoClient 在此处未定义。我还尝试将 MongoClient.connect() 调用包装在异步函数中，然后调用它，但这也无济于事。

有人对我应该尝试什么有想法吗？

Answer 1

我通过以下方式解决了这个问题：

1. 遵循Jest docs 的指示。如果您在test.js 文件中将其分配给app.locals，您仍然可以通过req.app.locals 访问MongoDB 连接。
2. 将我的MongoClient.connect() 电话转入app.js：

if(process.env.NODE_ENV === 'production'){
    MongoClient.connect(...)
}