使用 Jest、Supertest、MongoDB 和 Express 進行測試時出現的拆卸錯誤

Question

我正在使用 Jest 和 Supertest 測試我的 Express 路線。 在設置應用程序時，我還連接到 MongoDB 並將 MongoClient 添加到app.locals 。

我收到一個錯誤，當我注釋掉對 MongoClient 的調用時，該錯誤不會發生。

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)

當我注釋掉我的 MongoClient 調用時，我收到了這個 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.

這是我的測試腳本和應用程序模塊

應用程序.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;

測試.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);
    });
});

我嘗試在測試用例后使用app.locals.mongoClient.close()關閉與 MongoDB 的連接，但此處未定義mongoClient 。 我還嘗試將MongoClient.connect()調用包裝在異步 function 中，然后調用它，但這也無濟於事。

有人對我應該嘗試什么有想法嗎？

Answer 1

我通過以下方式解決了這個問題：

1. 按照Jest 文檔的說明進行操作。 如果您將它分配給app.locals文件中的test.js ，您仍然可以通過req.app.locals訪問 MongoDB 連接。
2. 在app.js中封裝了我的MongoClient.connect()調用：

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