Node process.domain behavior broken when running code using Jest

[harelmo]

🐛 Bug Report

Jest seems to modify the process object in such a way that breaks the ability to run code inside a domain - i.e., process.domain does not change to be the current domain set by calling the enter() method of a domain or running an arbitrary code through the run() method.

• I know this feature is deprecated in node, yet we still have some production-code using it heavily - so suggestions to stop using this modules are unfortunately invaluable at the moment.

To Reproduce

Steps to reproduce the behavior:

Run jest with the following spec file (not setup or actual production-code required):

const domain = require('domain')

describe('node domain', () => {
  test('should show that the current domain is used when running a function using domain.run(...)', () => {
    const d = domain.create()
      
    d.run(() => {
        expect(process.domain).not.toBeNull()
    })
  })
})

Expected behavior

The test above should pass, since process.domain should be set to the actual domain object in which the code is being run. See https://nodejs.org/docs/latest-v8.x/api/domain.html#domain_domain_enter.

Running the test in mocha + chai (with the relevant changes to the test only - requiring expect from chai and changing the matcher to not.to.be.null) results in a passing test.

Link to repl or repo

https://repl.it/@HarelMoshe/testNodeDomains

Output from npx envinfo --preset jest:

 System:
    OS: macOS High Sierra 10.13.2
    CPU: x64 Intel(R) Core(TM) i7-7820HQ CPU @ 2.90GHz
  Binaries:
    Node: 8.12.0 - ~/.nvm/versions/node/v8.12.0/bin/node
    Yarn: 1.6.0 - /usr/local/bin/yarn
    npm: 5.10.0 - ~/.nvm/versions/node/v8.12.0/bin/npm
  npmPackages:
    jest: ^23.6.0 => 23.6.0

[SimenB]

I doubt we'll spend time implementing support for domains in Jest seeing as it's deprecated. However, if the diff is minimal, a PR is of course welcome 🙂 The process object is created here: https://github.com/facebook/jest/blob/5eb9d36687d01059570182c4f33fef6e431dbaf5/packages/jest-util/src/create_process_object.js

[harelmo]

Thanks for pointing me to that code @SimenB - it actually made me think about a workaround to make the process object have the domain-related code attached to it prior to Jest performing the copy.
All I had to do is create a global-setup file exporting the following:

test/setup/global-setup.js:

module.exports = () => { require('domain') }

and use it as the global-setup file in my jest.config.js file:

module.exports = {
  globalSetup: `test/setup/global-setup.js`
}

Since require-ing the domain module has the side-effect on process in the global-setup phase - i.e., prior to Jest making its copy - that logic is persisted to the copy and everything seems to work fine.

[SimenB]

For anyone subscribed: should be fixed in #9136 which will come in Jest 25

[mapleeit]

Hi, @SimenB . Could you update jest@next on npm? Seems it's still a version published 3 months ago.

[mapleeit]

ping @SimenB

[github-actions]

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