Getting "You are trying to import a file after the Jest environment has been torn down" and "right-hand side of instanceof is not callable" in jest

Question

I'm trying to test a mongodb application but jest is throwing some errors my way here's the code for the file i'm testing I inserted a dummy function: testFunct() that just returns one for sanity purposes

const User = require("./database/database.js");
const client = require("./twitch/twitch.js");
const chalk = require("chalk");

var peopleWatching = new Object();

client.on("join", (channel, username, self) => {
  if (!self) {
    newUser(username);
  }
});

client.on("message", (channel, user, message, self) => {
  var name = user["display-name"];

  if (peopleWatching[name]) {
    peopleWatching[name].messagesSent++;
  } else {
    newUser(name);
  }
});

client.on("part", (channel, name, self) => {
  if (peopleWatching[name]) {
    data = peopleWatching[name];

    updateUser(data, name);
  } else {
    console.log(
      chalk.black.bgKeyword("darkorange")("WARN") +
        " untracked user " +
        chalk.underline(name) +
        " left the channel"
    );
  }
});

async function newUser(name) {
  var newUser = new User({ uName: name });
  await newUser
    .save()
    .then((val) => {
      console.log(
        chalk.black.bgGreen("NEW") +
          " " +
          chalk.underline(name) +
          " " +
          chalk.green("Has been added to the database")
      );
    })
    .catch(async (err) => {
      console.log(
        chalk.bgRed("ERR!") +
          ` ${chalk.underline(name)} already in the database`
      );
      newUser = await User.findOne({ uName: name });
    });

  if (!peopleWatching[name]) {
    peopleWatching[name] = {
      user: newUser,
      timeJoined: Date.now() / 1000,
      messagesSent: 0,
    };
  } else {
    // This person already exists
  }
}

async function updateUser(data, name) {
  user = data.user;
  messages = data.messagesSent;
  timeWatched = (Date.now() / 1000 - data.timeJoined)/60;

  user.messagesSent += messages;
  user.timeWatched += timeWatched;
  user.save();
  peopleWatching[name] = undefined;
  console.log(
    chalk.black.bgCyan("UPD") +
      " " +
      chalk.underline(name) +
      " " +
      chalk.green("Has been updated")
  );
}

function testFunct(){
    return 1;
}

module.exports = {testFunct,updateUser,newUser}

and the code for the test. currently i'm only testing my dummy function

const {testFunct,updateUser,newUser} = require('./index.js')
const jestConfig = require('./jest.config.js')

jest.useFakeTimers()
test("First test",()=>{
    expect(testFunct()).toBe(1)
})

and finally, the output from npm run test

npm run test

> [email protected] test C:\Users\brand\repos\kamiBot
> jest

 PASS  ./index.test.js
  √ First test (2 ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        1.188 s, estimated 2 s
Ran all test suites.

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

      at BufferList.Readable (node_modules/readable-stream/lib/_stream_readable.js:179:22)
      at BufferList.Duplex (node_modules/readable-stream/lib/_stream_duplex.js:67:12)
      at new BufferList (node_modules/bl/bl.js:33:16)
      at new MessageStream (node_modules/mongodb/lib/cmap/message_stream.js:35:21)
      at new Connection (node_modules/mongodb/lib/cmap/connection.js:54:28)
C:\Users\brand\repos\kamiBot\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 (C:\Users\brand\repos\kamiBot\node_modules\readable-stream\lib\_stream_readable.js:111:25)
    at BufferList.Readable (C:\Users\brand\repos\kamiBot\node_modules\readable-stream\lib\_stream_readable.js:183:25)
    at BufferList.Duplex (C:\Users\brand\repos\kamiBot\node_modules\readable-stream\lib\_stream_duplex.js:67:12)
    at new BufferList (C:\Users\brand\repos\kamiBot\node_modules\bl\bl.js:33:16)
    at new MessageStream (C:\Users\brand\repos\kamiBot\node_modules\mongodb\lib\cmap\message_stream.js:35:21)
    at new Connection (C:\Users\brand\repos\kamiBot\node_modules\mongodb\lib\cmap\connection.js:54:28)
    at C:\Users\brand\repos\kamiBot\node_modules\mongodb\lib\core\connection\connect.js:36:29
    at callback (C:\Users\brand\repos\kamiBot\node_modules\mongodb\lib\core\connection\connect.js:280:5)
    at Socket.connectHandler (C:\Users\brand\repos\kamiBot\node_modules\mongodb\lib\core\connection\connect.js:325:5)
    at Object.onceWrapper (events.js:421:28)
    at Socket.emit (events.js:315:20)
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1127:10)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] test: `jest`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the [email protected] test script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\brand\AppData\Roaming\npm-cache\_logs\2021-03-26T13_46_29_769Z-debug.log

I made sure to read the mongoose documentation and I made sure to configure jest.config.js just like the docs said to

Answer 1

Being older and wiser, I now understand that we should avoid side-effects in unit tests. Instead, we should stub functions that have side effects (like network, database or filesystem) using a library like sinon