Version: Deno 1.41.2

Description

Deno correctly registers SIGINT and other SIG* signals with process.on('SIGINT') via node:process imports, but the listeners are not appended to process.listeners('SIGINT') return array. This differs from the original Node.js implementation behavior and causes issues with libraries such as signal-exit@3.0.7

Reproduction Steps

import process from "node:process";

process.on('customEvent', () => console.log('customEvent'))
console.log(process.listeners('customEvent')) // outputs [ [Function (anonymous)] ]

process.on('SIGINT', () => console.log('SIGINT'))
console.log(process.listeners('SIGINT')) // outputs [], but it should also contain an anonymous function 

setTimeout(() => {}, 10000)

Explanation

Since Deno uses a custom implementation for handling OS Signals, a specific condition was added to the process polyfill to redirect all process.on() calls for SIG* signals to use Deno.addSignalListener(). However, the method responsible for adding the listener to the array is located at super.on() (in the EventEmitter class), which is never called.

Possible Fix

One possible fix would be to add the super.on(event, listener); call right after the Deno.addSignalListener() line, but I am not sure whether this would cause unintended side-effects between Deno and the polyfill.

Thanks for building Deno!