const { MongoClient, ObjectId } = require('mongodb');

void async function() {
  const client = await MongoClient.connect('mongodb://localhost:27017/test', {
    useNewUrlParser: true,
    useUnifiedTopology: true
  });

  const db = client.db();

  const replacement = {
    $internalProperty: 42,
    toBSON: () => ({ answer: 42 })
  };

  await db.collection('Test').bulkWrite([{
    replaceOne: { filter: { name: 'bar' }, replacement }
  }]);

  console.log('Done');
  process.exit(0);
}();