moment.utc drops time part when used as mongoose default

[ErikaA4]

Describe the bug
When we create a date field and default it to moment.utc, when it gets populated the date part of the timestamp is correct, but the time part gets lost and defaulted to midnight.

To Reproduce
Steps to reproduce the behavior:
Run the attached script.

const mongoose = require('mongoose');
const moment = require('moment');

main().catch(err => console.log(err)).then();

async function main() {
  await mongoose.connect('mongodb://localhost:27017/test');

  const kittySchema = new mongoose.Schema({
    birthday: {default: moment.utc, type: Date}
  });

  const Kitten = mongoose.model('Kitten', kittySchema);

  const cat = new Kitten({});
  console.log(cat);
 }

Expected behavior
Timestamp to be set to now with hour, minute and second correctly displayed (not zero).
Got this:

Erikas-Macbook:BUG erikaarnocki$ ts-node bug.ts
{
  _id: new ObjectId("61e5471c712520a0f39ebbef"),
  birthday: 2022-01-17T00:00:00.000Z
}

Expected:

Erikas-Macbook:BUG erikaarnocki$ ts-node bug.ts
{
  _id: new ObjectId("61e5471c712520a0f39ebbef"),
  birthday: 2022-01-17T10:39:40.000Z
}

Desktop:

• ts-node v8.10.2

Moment-specific environment

• The time zone setting of the machine the code is running on

Erikas-Macbook:BUG erikaarnocki$ locale
LANG="en_GB.UTF-8"
LC_COLLATE="en_GB.UTF-8"
LC_CTYPE="en_GB.UTF-8"
LC_MESSAGES="en_GB.UTF-8"
LC_MONETARY="en_GB.UTF-8"
LC_NUMERIC="en_GB.UTF-8"
LC_TIME="en_GB.UTF-8"
LC_ALL=

• The time and date at which the code was run
  Mon 17 Jan 2022 10:32:37 GMT
• Other libraries in use (TypeScript, Immutable.js, etc)

{
  "devDependencies": {
    "@types/node": "^17.0.9",
    "cypress-wait-until": "^1.7.1"
  },
  "dependencies": {
    "moment": "^2.29.1",
    "mongoose": "^6.1.6",
    "typescript": "^4.5.4"
  }
}

Please run the following code in your environment and include the output:

console.log((new Date()).toString())
console.log((new Date()).toLocaleString())
console.log((new Date()).getTimezoneOffset())
console.log(navigator.userAgent)
console.log(moment.version)

Erikas-Macbook:BUG erikaarnocki$ ts-node
> console.log((new Date()).toString())
Mon Jan 17 2022 10:33:56 GMT+0000 (Greenwich Mean Time)
undefined
> console.log((new Date()).toLocaleString())
17/01/2022, 10:33:56
undefined
> console.log((new Date()).getTimezoneOffset())
0
undefined
> console.log(navigator.userAgent)
/Users/erikaarnocki/BUG/[eval].ts:1
console.log(navigator.userAgent);
            ^

Uncaught ReferenceError: navigator is not defined
    at /Users/erikaarnocki/BUG/[eval].ts:1:13
    at Script.runInThisContext (vm.js:133:18)
    at exec (/usr/local/lib/node_modules/ts-node/src/bin.ts:347:17)
    at /usr/local/lib/node_modules/ts-node/src/bin.ts:337:27
    at Array.reduce (<anonymous>)
    at _eval (/usr/local/lib/node_modules/ts-node/src/bin.ts:336:18)
    at REPLServer.replEval (/usr/local/lib/node_modules/ts-node/src/bin.ts:387:16)
    at bound (domain.js:413:15)
    at REPLServer.runBound [as eval] (domain.js:424:12)
    at REPLServer.onLine (repl.js:817:10)

[ErikaA4]

Opened ticket to mongoose as well.
Automattic/mongoose#11233

[DiscoNova]

Whenever You use a temporal component in Your tests (like the "current date/time", which moment.utc()-method internally uses) ... You should be prepared to mock the native Date-implementation of JavaScript to return the expected Date/Time whenever called in Your tests. Otherwise Your tests will fail tomorrow, a minute from now, etc.

This is not an issue with Moment and it is not an issue with mongoose. You just need a bit of prerun setup on Your test ;)