mongoose auto-increment field on creation with middleware

Test.js

const mongoose = require('mongoose')

const testSchema = new mongoose.Schema({
    id: {
        type: Number,
        unique: true,
        required: true,
        min: 1,
    },
})

const testModel = mongoose.Model('Test', testSchema)

// Middleware to enforce auto-increment of Test.id
testSchema.pre('save', async next => {
    if (this.isNew) {
        this.id = await testModel.count()
    } else {
        next()
    }
})

module.exports = testModel