Node 12 process.removeListener is not a function

Prerequisites

• Checked that your issue hasn’t already been filed by cross-referencing issues with the faq label
• Checked next-gen ES issues and syntax problems by using the same environment and/or transpiler configuration without Mocha to ensure it isn’t just a feature that actually isn’t supported in the environment in question or a bug in your code.
• ‘Smoke tested’ the code to be tested by running it outside the real test suite to get a better sense of whether the problem is in the code under test, your usage of Mocha, or Mocha itself
• Ensured that there is no discrepancy between the locally and globally installed versions of Mocha. You can find them with: node node_modules/.bin/mocha --version(Local) and mocha --version(Global). We recommend that you not install Mocha globally.

Description

Running unit tests with "mocha": "6.1.4", on my repository along with Node v12.0.0 results in error process.removeListener is not a function

This error does not occur with Node v10.15.1

Steps to Reproduce

I suspect the error will occur any time you run unit tests with mocha along with Node 12, but here’s a way:

1. Clone my repository: git clone https://github.com/whyboris/karma-helpful-reporter.git

2. Install Node v12.0.0 (I’m using nvm to switch back between versions easily)

3. Then npm run test and see the error. Note that the error does not occur on Node v10.

Expected behavior: [What you expect to happen] No error with Node 12

Actual behavior: [What actually happens]

    process.removeListener('uncaughtException', uncaught);
            ^

TypeError: process.removeListener is not a function

Reproduces how often: [What percentage of the time does it reproduce?] Every time

Versions

“mocha”: “6.1.4”, Node v12.0.0

• The output of mocha --version and node node_modules/.bin/mocha --version: 6.1.4
• The output of node --version: v12.0.0
• Your operating system
  • name and version: Mac OS 10.14.6
  • architecture (32 or 64-bit): 64bit
• Your shell (e.g., bash, zsh, PowerShell, cmd): zsh
• Your browser and version (if running browser tests): n/a
• Any third-party Mocha-related modules (and their versions): n/a (?)
• Any code transpiler (e.g., TypeScript, CoffeeScript, Babel) being used (and its version): TypeScript (?)

Additional Information

Full log:

  1) "after each" hook
/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:917
    process.removeListener('uncaughtException', uncaught);
            ^

TypeError: process.removeListener is not a function
    at Runner.<anonymous> (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:917:13)
    at Runner.emit (events.js:196:13)
    at /Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:903:12
    at done (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:761:7)
    at next (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:728:16)
    at done (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:761:7)
    at next (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:732:14)
    at done (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:761:7)
    at next (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:732:14)
    at done (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:761:7)
    at next (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:732:14)
    at done (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:761:7)
    at next (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:732:14)
    at Runner.hookErr (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:575:7)
    at Runner.uncaught (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:857:19)
    at process.uncaught (/Users/byakubchik/Desktop/temp/karma-helpful-reporter/node_modules/mocha/lib/runner.js:887:10)
    at process.emit (events.js:196:13)
    at process._fatalException (internal/process/execution.js:146:25)

Node documentation for removeListener: https://nodejs.org/api/events.html#events_event_removelistener [edit] - documentation should be here, thank you @plroebuck : https://nodejs.org/api/events.html#events_emitter_removelistener_eventname_listener

[Munter]

I can recreate the error by cloning [e-mail]:whyboris/karma-helpful-reporter, creating a clean install on node 12.13.0 and running the test suite:

$ npm t

> karma-helpful-reporter@0.3.4 test /Users/pbm/git/karma-helpful-reporter
> nyc mocha



[REMOVED SUCCESSFUL TESTS OUTPUT]


  105 passing (1s)

  1) "after each" hook
/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:917
    process.removeListener('uncaughtException', uncaught);
            ^

TypeError: process.removeListener is not a function
    at Runner.<anonymous> (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:917:13)
    at Runner.emit (events.js:210:5)
    at /Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:903:12
    at done (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:761:7)
    at next (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:728:16)
    at done (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:761:7)
    at next (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:732:14)
    at done (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:761:7)
    at next (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:732:14)
    at done (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:761:7)
    at next (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:732:14)
    at done (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:761:7)
    at next (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:732:14)
    at Runner.hookErr (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:575:7)
    at Runner.uncaught (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:857:19)
    at process.uncaught (/Users/pbm/git/karma-helpful-reporter/node_modules/mocha/lib/runner.js:887:10)
    at process.emit (events.js:210:5)
    at processEmit [as emit] (/Users/pbm/git/karma-helpful-reporter/node_modules/signal-exit/index.js:155:32)
    at process._fatalException (internal/process/execution.js:150:25)

[mikeebowen]

I’m also seeing exactly the same issue with mocha tests in node 12.12.0 and the screenshot above is what I also see.