jest: Using lodash causes "open handles" warnings

🐛 Bug Report

Something about Lodash causes Jest to detect “open handles”

To Reproduce

Run jest with --detectOpenHandles and require lodash. I’m not sure what the exact conditions going on here, but it’s pretty reliably reproducible with the repo below.

The behavior looks like this:


Jest has detected the following 2 open handles potentially keeping Jest from exiting:

  ●  PROMISE

          at Function.resolve (<anonymous>)
      at Object.<anonymous> (node_modules/lodash/_getTag.js:37:32)


  ●  PROMISE

      1 | "use strict";
      2 | Object.defineProperty(exports, "__esModule", { value: true });
    > 3 | require("lodash");
        | ^
      4 | describe(`lodash`, () => {
      5 |     it(`causes these tests to show open handles`, () => {
      6 |         expect(1).toEqual(1);

          at Function.resolve (<anonymous>)
      at runInContext (node_modules/lodash/lodash.js:6069:36)
      at Object.<anonymous> (dist/test/do-lodash-things.js:3:1)

Expected behavior

I wouldn’t expect to see open handles for require() calls

Link to repo

git clone https://github.com/alexturek/jest-lodash-handles-bug
cd jest-lodash-handles-bug
yarn
tsc
yarn test

Run `npx envinfo --preset jest`

aturek@aturek-mbpro ~/oss/jest-lodash-handles-bug> npx envinfo --preset jest
npx: installed 1 in 3.361s

  System:
    OS: macOS High Sierra 10.13.5
    CPU: x64 Intel(R) Core(TM) i5-5257U CPU @ 2.70GHz
  Binaries:
    Node: 8.9.1 - ~/.nvm/versions/node/v8.9.1/bin/node
    Yarn: 1.7.0 - ~/.yarn/bin/yarn
    npm: 5.5.1 - ~/.nvm/versions/node/v8.9.1/bin/npm
  npmPackages:
    @types/jest: ^23.1.4 => 23.1.4
    jest: 23.3.0 => 23.3.0

About this issue

Original URL
State: closed
Created 6 years ago
Reactions: 25
Comments: 18 (11 by maintainers)

Commits related to this issue

chore(deps): update jest to v23.5.0 This resolves an issue with jest that was preventing tests from completing on windows environments. See https://github.com/facebook/jest/issues/6639 — committed to mrfelton/zap-desktop by mrfelton 6 years ago

Most upvoted comments

Consistently seeing the same issue:

Jest has detected the following 1 open handle potentially keeping Jest from exiting:

  ●  PROMISE

          at Function.resolve (<anonymous>)
      at Object.<anonymous> (node_modules/lodash/_getTag.js:37:32)
      at Object.<anonymous> (node_modules/lodash/isEmpty.js:2:14)

+11

caseyrule on Jul 10, 2018

As mentioned there, I think the fix is to ignore promises as they don’t keep the process open anyways

SimenB on Jul 19, 2018

@SimenB I might be able to spend time on a fix. What’s the package I should start in? jest-cli/.../collectHandles.js ?

alexturek on Jul 20, 2018

@SimenB Maybe I had to explain why I think some of the stack traces that I posted seem related to me.

lodash and sequelize stack traces end up in the Function.resolve call. Couldn’t this be caused by the same issue ? Thought this could be useful.

I’m removing the other stack trace so that it doesn’t generate confusion.

bilby91 on Jul 11, 2018

Running into multiple of this issues on jest 23.4.0

  ●  PROMISE

          at Function.resolve (<anonymous>)
      at Object.<anonymous> (node_modules/lodash/_getTag.js:37:32)
      at Object.<anonymous> (node_modules/lodash/isEmpty.js:2:14)


  ●  PROMISE

          at Function.resolve (<anonymous>)
      at Function.runInContext (node_modules/lodash/lodash.js:6088:36)
      at Object.<anonymous> (node_modules/sequelize/lib/dialects/abstract/query-generator.js:19:40)
      at Object.<anonymous> (node_modules/sequelize/lib/dialects/postgres/query-generator.js:6:32)