invalidate.js

var mongoose = require('mongoose');
mongoose.connect('localhost', 'testing_invalidate');

var schema = new mongoose.Schema({
  name: { type: String, required: true },
  pass: { type: String, required: true },
});

schema.methods.setPassword = function setPassword (pwd, confirm) {
  if (pwd === confirm) {
    this.pass = pwd;
    return true;
  }
  this.invalidate('password', new Error('Password mismatch'));
  return false;
}

var A = mongoose.model('A', schema);

mongoose.connection.on('open', function () {
  var a = new A({ name: 'jxck' });
  a.setPassword('xxx', 'xxx');
  a.save(function (err) {
    if (err) console.log(err);
    // { message: 'Validation failed',
    //   name: 'ValidationError',
    //   errors: 
    //    { password: [Error: Password mismatch],
    //      pass: 
    //       { message: 'Validator "required" failed for path pass',
    //         name: 'ValidatorError',
    //         path: 'pass',
    //         type: 'required' } } }
    mongoose.connection.db.dropDatabase(function () {
      mongoose.connection.close();
    });
  });
});