Something that might be worth a try:
const {ObjectId} = require('mongodb');
I have no experience with const SchemaTypes = mongoose.Schema.Types;
, but I know the above method to create an ObjectId works.
Just to help you debug, this is the expected user object in full:
const expected = {
username: 'fcc_test_1596648410971', // Obviously the numbers change
description: 'test',
duration: 60,
_id: 5f29cd9e782d5f13d127b456, // Must be of type 'ObjectId'
date: 'Mon Jan 01 1990'
}